Bengali language support as OS locale

Yes, Bengali is indeed supported.

How did you install the language pack? The prefered way to install a new language is via

System Settings -> Language Support -> Install / Remove Languages...

I suggest that you try to install Bengali that way. (If it's already checked, you need to remove it first.)

@Gunnar : Thanks for the reply. Yes. I did install this through System Settings -> Language Support -> Install / Remove Languages...

And if I go to Install / Remove Languages it shows as installed. But it does not appear under "Language for menus and windows".
So, after I read your instructions, I unchecked (uninstalled) Bengali through System Settings -> Language Support -> Install / Remove Languages... and added it again. And even restarted the system (though I don't eally think that was necessary).

But still, under "Language for menus and windows", I do not see Bengali !
I could not find an option for attachments here, else I could have shared the screenshot from my system.

That's strange.

Can you please run the following three commands from a terminal window, and let us know the output:

  ll /usr/share/locale-langpack

  locale -a

  /usr/share/language-tools/language-options

siddhartha@siddhartha-Notebook-PC:~$ ll /usr/share/locale-langpack
total 232
drwxr-xr-x 56 root root 4096 Jan 26 04:53 ./
drwxr-xr-x 296 root root 12288 Jan 26 04:52 ../
drwxr-xr-x 3 root root 4096 Jan 22 17:10 ar/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 be/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 ber/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 bg/
drwxr-xr-x 3 root root 4096 Jan 26 04:53 bn/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 ca/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 ca@valencia/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 cs/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 de/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 el/
drwxr-xr-x 3 root root 4096 Oct 17 20:30 en/
drwxr-xr-x 3 root root 4096 Oct 17 20:30 en_AU/
drwxr-xr-x 3 root root 4096 Oct 17 20:30 en@boldquot/
drwxr-xr-x 3 root root 4096 Oct 17 20:30 en_CA/
drwxr-xr-x 3 root root 4096 Oct 17 20:30 en_GB/
drwxr-xr-x 3 root root 4096 Oct 17 20:30 en_NZ/
drwxr-xr-x 3 root root 4096 Oct 17 20:30 en@quot/
drwxr-xr-x 3 root root 4096 Oct 17 20:30 en@shaw/
drwxr-xr-x 3 root root 4096 Oct 17 20:30 en_US/
drwxr-xr-x 3 root root 4096 Oct 17 20:30 en_US@piglatin/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 es/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 et/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 eu/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 fi/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 fr/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 gl/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 he/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 hr/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 hu/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 is/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 it/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 ja/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 ko/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 lt/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 lv/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 nl/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 pl/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 pt/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 pt_BR/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 ro/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 ru/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 si/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 sk/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 sl/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 sr/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 sr@latin/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 sv/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 ta/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 te/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 tr/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 uk/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 vi/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 zh_CN/
drwxr-xr-x 3 root root 4096 Jan 22 17:10 zh_TW/

siddhartha@siddhartha-Notebook-PC:~$ locale -a
C
C.UTF-8
en_AG
en_AG.utf8
en_AU.utf8
en_BW.utf8
en_CA.utf8
en_DK.utf8
en_GB.utf8
en_HK.utf8
en_IE.utf8
en_IN
en_IN.utf8
en_NG
en_NG.utf8
en_NZ.utf8
en_PH.utf8
en_SG.utf8
en_US.utf8
en_ZA.utf8
en_ZM
en_ZM.utf8
en_ZW.utf8
POSIX
zh_CN.utf8
zh_SG.utf8

siddhartha@siddhartha-Notebook-PC:~$ /usr/share/language-tools/language-options
en
en_AU
en_CA
en_GB
en_NZ
en_US
zh_CN

Thanks for the info. The Bengali locales are missing, which is a mystery since they should have been created when you installed the Bengali language.

Anyway, to fix it I suggest that you first try to run

  sudo locale-gen

from a terminal window. If that doesn't help, try:

  sudo locale-gen bn_BD bn_IN

Please let us know if that worked.

I tried but it didn't work. I got the error below :
(I tried uninstall and install Bengali again through Language Support, and clicked to view details, and I saw the same error is encountered at the time of installation)

siddhartha@siddhartha-Notebook-PC:~$ sudo locale-gen
Generating locales...
  bn_BD.UTF-8... cannot open locale definition file `bn_BD': No such file or directory failed
  bn_IN.UTF-8... cannot open locale definition file `bn_IN': No such file or directory failed
  en_AG.UTF-8... done
  en_AU.UTF-8... done
  en_BW.UTF-8... done
  en_CA.UTF-8... done
  en_DK.UTF-8... cannot open locale definition file `da_DK': No such file or directory failed
  en_GB.UTF-8... done
  en_HK.UTF-8... done
  en_IE.UTF-8... done
  en_IN.UTF-8... cannot open locale definition file `hi_IN': No such file or directory failed
  en_NG.UTF-8... cannot open locale definition file `da_DK': No such file or directory failed
  en_NZ.UTF-8... done
  en_PH.UTF-8... cannot open locale definition file `tl_PH': No such file or directory failed
  en_SG.UTF-8... done
  en_US.UTF-8... done
  en_ZA.UTF-8... done
  en_ZM.UTF-8... done
  en_ZW.UTF-8... done
Generation complete.

siddhartha@siddhartha-Notebook-PC:~$ sudo locale-gen bn_BD bn_IN
Generating locales...
  bn_BD.UTF-8... cannot open locale definition file `bn_BD': No such file or directory failed
  bn_IN.UTF-8... cannot open locale definition file `bn_IN': No such file or directory failed
Generation complete.

Quite a few locale definition files seem to be missing on your system. Can you please let us know how Ubuntu was installed in the first place?

Now I suggest that you try

  sudo apt-get --reinstall install locales

and then

  sudo locale-gen bn_BD bn_IN

Ubuntu was installed from the iso downloaded from the official website. I dont know, if it has corrupted later on, by any other actions.

I got stuck on the re-installation. What can be done ? Do I need to get this from the iso image ?
This system is connected to the internet, so I do not understand why the it says - "cannot download". Do I need to add any extra repo for this ?

siddhartha@siddhartha-Notebook-PC:~$ sudo apt-get --reinstall install locales
Reading package lists... Done
Building dependency tree
Reading state information... Done
Reinstallation of locales is not possible, it cannot be downloaded.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

Thanks Gunnar Hjalmarsson, that solved my question.

I do appreciate all your help !

You're welcome. I can't help wondering, though, why locales was not completely installed.