Could you fill in this detail: where is your old Firefox, is it on a different computer?

If you did an installation of Windows 8 on the same computer that had your old Firefox:

Do you recall any questions posed by the installer about what to do with the data that was already on the hard drive? Some options may lead to a special folder being created.

To explore, you'll first need to turn on viewing of hidden files and folders: http://windows.microsoft.com/en-us/windows/show-hidden-files

Then check here:

C:\Windows.old\Users\your-user-name\AppData\Roaming\Mozilla\Firefox\Profiles

Assuming you find one or more folders there, one of them most likely will have your earlier Firefox data. Any luck?

If that doesn't exist, try a global search of your "C" drive for bookmarkbackups which is a standard Firefox folder. Hopefully you'll find more than just your new one.

sorry i can see hidden folder right now but i cannot see such directory of c:\\windows.old etc. how should i continue?what should i do?i installed windows 8 on same computer .data on my hard drive was formatted ,the data on drive that windows what not installed still stayed intact.i upgraded to windows 10 then my computer ran into problem that i needed to reset to factory to windows 8

canmoh said

data on my hard drive was formatted ,the data on drive that windows what not installed still stayed intact.

Um, normally your Firefox data is stored here:

C:\Users\username\AppData\Roaming\Mozilla\Firefox\Profiles

If you didn't intentionally move that folder to a different partition, it's probably gone and difficult to recover. There are tools to search for traces of old files, but they probably aren't very reliable in a case like this. You could try this one:

https://www.piriform.com/recuva

What you would hope to find is a file name starting with bookmarks-2016 and ending with .jsonlz4 (the rest of the file name would include month, date, number of bookmarks, and a long unique code). See how many of those Recuva can find, and hopefully one of them won't be corrupted.

Alternately, did you ever create a Firefox Account and set up the Sync service? That's really the only scenario in which your bookmarks would be stored with Mozilla. Otherwise, they are only on your computer and in any backups you might have made yourself.