This is a method which is built into Firefox for a forced restore of Bookmarks should they get corrupted

For a fuller examination of this subject please see here

This procedure makes uses of an internal functioning of Firefox.
If places.sqlite, which is the file where all Bookmarks are stored is deleted, Firefox automtically reconstructs a new Places.sqlite from its own automatic backups.[JSON}

To force this process to happen in the case of corrupted bookmarks.

1. First make sure that no Firefox Profiles are running at all on your computer.
2. Find the Corrupt Profile in question on your Hard Disk where you want to restore the bookmarks
3. When you find the right Profile look for the file places.sqlite, and also any places.sqlite-journal or places.sqlite.corrupt files.

And delete them.

Once deleted, exit your operating system, and simply re-start your Firefox.

On start up Firefox will automatically reconstitute your bookmarks [places.sqlite] from its own automated backup.

Hopefully you will find that your Bookmarks and your Fast Dial will have been automatically restored.

The only and rather small downside to this procedure is that past History will be erased.

Many thanks