Firefox doesn't keep any backups of browsing history, so there's no restore feature for it. What happened? Did Firefox report that a file was corrupted? If you are having problems with bookmarks or history, a locked or corrupted file could be the explanation. The first thing to try is to quit Firefox and start it up again. If you don't regain full bookmark/history functionality, then try a regular shutdown/restart of MacOS (this is to free any file locks and ensure that any transient app permission issues are resolved). Any improvement?