Set FF to restore session, after a crash session wouldn't restore no matter what i do. help!

already set FF to restore sessions previous. FF has been crashing a lot lately on me. it always restored the sessions until this recent time. a couple of times i had to restart the computer to be able to open FF again after a crash. i've tried to fresh FF once but that didn't help me restore the previous session as well. I had important tabs opened and want to restore it if it's possible. Please help.