Really sorry to hear that.
I find FF crashing so much that it has forced me to use Chrome in parallel, particularly for TW dev.
I suspect it is too late, but I use a FF addon called Form History Control that has occasionally been of value. It gives you control over filled in form fields and you might find some stuff in there but unlikely very much.
I also rely much on tiddlyspot for stuff, which has a backup system build in. Now with the nice TW5 encryption mechansims you can store more personal - but of course not sensitive - stuff there.
Other than that, it's a quick manual ctrl-c ctrl-v on the latest local TW file every now and then for me. Not ideal.
Grabbing for straws, but maybe you did at one time make a backup... maybe it's in a not-yet-emptied wastebasked... an email...?
Hope it works out somehow.
<;-)