cannot access my server with ssh

What mean cannot access ? Please give us more details on messages you get...

Then you said "But now I cannot access it with SSH (it is on my home network). " so ssh is working, might be a firewall configuration if you are trying to access via ssh from web.

Please give us details...

What I do is what I have been normaly doing (opening up Putty, typing the ip 192.168.254.3 and start the connection) but it times out.

can you ping the mentioned IP from other hosts on the network ?

in CMD I typed "ping 192.168.254.3" and it replied by switching it to 192.168.254.1 and saying "destination host is unreachable"

You cannot ssh to a host that is not reachable , if you are running any firewall than chances are that the firewall may be dropping your requests .You need to provide some more information on this .

I had tried to redo my firewall yeasterday using this guide ( http://library.linode.com/securing-your-server ) but I was getting an error saying something like "could not do line 33" (or something to that extent), but decided to leave that for another time, I assumed my firewall was not changed at all from the fresh OS install.

Do you have openssh-server package installed? Is it running. You can check with:

server ssh status

Thanks

when I do that command, it says " the program 'server' is currently not installed. You can install it by typing: apt-get install rsplib-tools"

Is that something I need?

As I was not far into everything, I have decided to reinstall the OS and start from scratch (4 days work is much quicker the second time round). But I have one question and then you can lock this. What is a proven to work guide for making the IP static?

sorry:

sudo service ssh status

You can ask your ISP to provide you with a static IP .
Else if you are having a dynamic one , then you can map your hostname to the dynamically changing IP .
 So here is how to use DynDNS hostname for your dynamic IP.

http://www.webupd8.org/2009/09/ssh-server-with-dynamic-ip-address-how.html