Well unless you backed up your Firefox profile folder [1] I'm afraid deleted history cannot be restored. Firefox does not save your data on other machines but your own hardware, if you tell it to - and that is one of the reasons which makes it secure.

[1] http://kb.mozillazine.org/Profile_folder_-_Firefox

However, you can prevent history deletion by navigating Options/Preferences -> Privacy -> "Remember history" or "Use custom settings for history"

If history is being lost after "Remember history" is selected, then we have a serious problem and I would kindly ask you to file a report in Bugzilla [2].

[2] http://bugzilla.mozilla.org

Hope it helps!

I'm assuming your History got Deleted and you want to Recover it? Unfortunately there isn't any way to do that besides running a file recovery deletion program (Such as Recuva) and that most likely work in this case.

Now, to keep History from being deleted, are you meaning to keep it from deleting automatically, or from keeping other people from deleting it?

Also, make sure you update to Firefox 14, Firefox 12 (what you are running) is vulnerable to many security issues.

You can't prevent others from deleting the history in Firefox.

If you want a record of visited sites then you need to use logging software that runs on your computer or use a router with a password protected logging feature.

I wish they would warn you on the install. I had a rich browsing history that I go back to, passwords, sites I've gone to - gone. Now my location bar has sites listed I haven't visited in 6 months but the daily routine sites I use for business are gone. I back everything up - except my profile. Maybe Chrome is the answer now. A browser upgrade should NEVER cause this kind of problem.