Firefox browser saves copy of bookmarks backup under :
C:\Documents and Settings\%username%\Application Data\Mozilla\Firefox\Profiles
under a directory looks like this :suifc6pf.default
Then under "bookmarkbackups" there are many *.json files.

To resore the bookmars:
1. open Firefox
2. oN main menu open Bookmarks and click "Organize bookmarks"
3. Click "Import and Backup"
4. Choose restor > select date