Can't update/upgrade anything

Why not do a clean install of Precise rather than upgrading and so forth? Precise is the latest LTS release and supported til April 2017.

Please read this site. Pay close attention to End Of Life dates.

https://wiki.ubuntu.com/Releases

Have you changed boot order in BIOS, so the computer will boot from DVD reader?
If you have older computer, check if the system requirements for 12.04 can be met by your computer. If it does not meet the requirements, check out Xubuntu or Lububtu. Both are listed at bottom of above site.

Last night I was able to update to 10.04. Somehow this time the update didn't cancel when it couldn't fetch some files but kept updating. Now I'm trying to update to 12.04 but i have the same problem, can't fetch some files so it doesn't update anything.
I can't do a clean install because autorun doesn't work, i e i can't use a dvd or cd for installing a new os.
From computer settings (when turning the PC on) it seems, that the dvd rom is 1st in boot order but it just doesn't do that.
I'll try to search in forums for solutions for the fetching problem... until something from there works, i'm still w/o a solution.

If you are already on Ubuntu 10.04 and want to upgrade to 12.04, you could just open a terminal (ctrl-alt-t) and issue the command

sudo do-release-upgrade

This should download all files required for the release upgrade and perform the update for your Ubuntu system.

If that fails, you should check the status of your current system by issuing the following commands:

uname -a
lsb_release -a
cat /etc/update-manager/release-upgrades
sudo apt-get update
sudo apt-get upgrade

Please select all output, copy it and paste into this question document that we can verify.

with the first one:
...
Hit http://ftp.estpak.ee precise-security/universe Translation-en
Fetched 0 B in 0s (0 B/s)

Error during update

A problem occurred during the update. This is usually some sort of
network problem, please check your network connection and retry.

W:Failed to fetch
http://ports.ubuntu.com/ubuntu-ports/dists/precise/main/binary-i386/Packages
404 Not Found
, E:Some index files failed to download. They have been ignored, or
old ones used instead.

second one:
dianx@lauakas:~$ uname -a
Linux lauakas 2.6.32-53-generic #115-Ubuntu SMP Wed Oct 23 17:28:40 UTC 2013 i686 GNU/Linux
dianx@lauakas:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 10.04.4 LTS
Release: 10.04
Codename: lucid
dianx@lauakas:~$ cat /etc/update-manager/release-upgrades
# Default behavior for the release upgrader.

[DEFAULT]
# Default prompting behavior, valid options:
#
# never - Never check for a new release.
# normal - Check to see if a new release is available. If more than one new
# release is found, the release upgrader will attempt to upgrade to
# the release that immediately succeeds the currently-running
# release.
# lts - Check to see if a new LTS release is available. The upgrader
# will attempt to upgrade to the first LTS release available after
# the currently-running one. Note that this option should not be
# used if the currently-running release is not itself an LTS
# release, since in that case the upgrader won't be able to
# determine if a newer release is available.
Prompt=lts
dianx@lauakas:~$ sudo apt-get update
Hit http://ftp.estpak.ee lucid Release.gpg
Hit http://ports.ubuntu.com lucid Release.gpg
Ign http://ports.ubuntu.com/ubuntu-ports/ lucid/main Translation-en_US
Ign http://ftp.estpak.ee/ubuntu/ lucid/main Translation-en_US
Ign http://ftp.estpak.ee/ubuntu/ lucid/restricted Translation-en_US
Ign http://ftp.estpak.ee/ubuntu/ lucid/universe Translation-en_US
Ign http://ftp.estpak.ee/ubuntu/ lucid/multiverse Translation-en_US
Hit http://ftp.estpak.ee lucid-updates Release.gpg
Hit http://ports.ubuntu.com lucid Release
Ign http://ftp.estpak.ee/ubuntu/ lucid-updates/main Translation-en_US
Ign http://ftp.estpak.ee/ubuntu/ lucid-updates/restricted Translation-en_US
Ign http://ftp.estpak.ee/ubuntu/ lucid-updates/universe Translation-en_US
Ign http://ftp.estpak.ee/ubuntu/ lucid-updates/multiverse Translation-en_US
Hit http://ftp.estpak.ee lucid-security Release.gpg
Ign http://ftp.estpak.ee/ubuntu/ lucid-security/main Translation-en_US
Ign http://ftp.estpak.ee/ubuntu/ lucid-security/restricted Translation-en_US
Ign http://ftp.estpak.ee/ubuntu/ lucid-security/universe Translation-en_US
Ign http://ftp.estpak.ee/ubuntu/ lucid-security/multiverse Translation-en_US
Hit http://ftp.estpak.ee lucid Release
Ign http://ports.ubuntu.com lucid/main Packages
Hit http://ftp.estpak.ee lucid-updates Release
Ign http://ports.ubuntu.com lucid/main Packages
Err http://ports.ubuntu.com lucid/main Packages
  404 Not Found
Hit http://ftp.estpak.ee lucid-security Release
Hit http://ftp.estpak.ee lucid/main Packages
Hit http://ftp.estpak.ee lucid/restricted Packages
Hit http://ftp.estpak.ee lucid/main Sources
Hit http://ftp.estpak.ee lucid/restricted Sources
Hit http://ftp.estpak.ee lucid/universe Packages
Hit http://ftp.estpak.ee lucid/universe Sources
Hit http://ftp.estpak.ee lucid/multiverse Packages
Hit http://ftp.estpak.ee lucid/multiverse Sources
Hit http://ftp.estpak.ee lucid-updates/main Packages
Hit http://ftp.estpak.ee lucid-updates/restricted Packages
Hit http://ftp.estpak.ee lucid-updates/main Sources
Hit http://ftp.estpak.ee lucid-updates/restricted Sources
Hit http://ftp.estpak.ee lucid-updates/universe Packages
Hit http://ftp.estpak.ee lucid-updates/universe Sources
Hit http://ftp.estpak.ee lucid-updates/multiverse Packages
Hit http://ftp.estpak.ee lucid-updates/multiverse Sources
Hit http://ftp.estpak.ee lucid-security/main Packages
Hit http://ftp.estpak.ee lucid-security/restricted Packages
Hit http://ftp.estpak.ee lucid-security/main Sources
Hit http://ftp.estpak.ee lucid-security/restricted Sources
Hit http://ftp.estpak.ee lucid-security/universe Packages
Hit http://ftp.estpak.ee lucid-security/universe Sources
Hit http://ftp.estpak.ee lucid-security/multiverse Packages
Hit http://ftp.estpak.ee lucid-security/multiverse Sources
W: Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/lucid/main/binary-i386/Packages.gz 404 Not Found

E: Some index files failed to download, they have been ignored, or old ones used instead.
dianx@lauakas:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

Restoring original system state

Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
Building data structures... Done

when i press check in update manager:
Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/lucid/main/binary-i386/Packages.gz 404 Not Found
Some index files failed to download, they have been ignored, or old ones used instead.

when trying to upgrade to 12.04 while setting new software channels:
W:Failed to fetch http://ports.ubuntu.com/ubuntu-ports/dists/precise/main/binary-i386/Packages 404 Not Found
, E:Some index files failed to download. They have been ignored, or old ones used instead.
so the same...

I suggest you boot to the Precise install CD, you will be offered an upgrade option

Apparently you have erroneously an extra server mentioned in your list of servers from where software can be downloaded from.
Ubuntu-ports is a project to provide Ubuntu also for systems with other processors than the widely-used Intel x86 and AMD64 architecture. As your system apparently works well with the i686 software, you do not need that extra server at all.

Please open a terminal and execute the following command:

find /etc/apt -name '*.list' -exec bash -c 'echo -e "\n$1\n"; cat -n "$1"' _ '{}' \;

then copy/paste all output that we can provide instructions how to correct that.