Ever heard of about:sessionrestore
It lists all the tabs and windows of the last session in case the last session was crashed.
So you can use it if you do not get an option to restore your previous session after a crash.
In Firefox, typing "about:sessionrestore" in the address bar gives the following screen:
Works in Firefox 3.5.6
Note: It may work in other versions as well though I have only tested it in 3.5.6
