What is it you are trying to change? the spelling options of Firefox spell checker, or the language of all the User Interface displays ?

I not that you are using an old and unsupported version of Firefox, so it should be updated anyway, it is not secure, you are on version Fx7 you should by now be on Fx18. (Unless you are using corporate/educational institute versions)

1. Download a version from here http://www.mozilla.org/en-US/firefox/all/
2. As a precaution you may wish to backup your profile first
   Back up and restore information in Firefox profiles
   It is good practice to do that occasionally anyway.
3. follow these instructions
   How to install Firefox on Windows
   Take care NOT to use any option that removes personal information, because that will destroy bookmarks, passwords and settings.

Also see

• .Settings for web content, pop-ups, fonts, and languages_languages

Please post back with how you get on.

i want to change browser language from hindi to english .

If the Firefox user interface (menu bar) is in the wrong language or if you want to change the current language then you can get Firefox in the language of your choice here:

• Firefox 18.0.x: http://www.mozilla.com/en-US/firefox/all.html

You can check the order of the installed Languages.

• Tools > Options > Content > Languages