hello, this obviously depends on how you have backed up your personal data before you reinstalled the OS. your bookmarks are stored within the firefox profile: Recovering important data from an old profile

Hi

Where can I find the Firefox profile. I have not manually backed up the bookmarks before I reinstalled.

Thanks

normally it will be stored in C:\Users\<Windows user name>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile folder> - however i don't know how reinstalling the OS might has affected that (maybe it got overwritten).

On your system, can you find a folder named:

C:\Windows.old\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles\

If so, Windows kept a backup of your old Firefox settings folder (profile folder) during the reinstall.

Edit: Here's an example of someone using that folder to recover bookmarks: After upgrading to Windows 8 Pro, I've lost all of the FireFox bookmarks. Internet Explorer bookmarks are intact. How can I restore firebox bookmarks?

Hi

I can't find that location.

In case the AppData folder is hidden on your system, have you enabled viewing of hidden files and folders?

http://windows.microsoft.com/en-us/windows-vista/show-hidden-files

I found the location. From there onwards what do I do?

Did you find the new location (no useful data) or the windows.old location (your old data)? If you found the old data, check out the above link to the thread about the user who was able to restore that data. The steps for bookmark restore are described in this article: Restore bookmarks from backup or move them to another computer.