Portable Bird removed my data and tried to re-install

This has happened to me before, but I figured it wasn't anything to bother with too much since I had a backup from a couple days before, but this time it's bad. Also I figure it's a bad problem since it happened again so quickly (about 7 weeks).
The problem is this: I was using thunderbird (with lightning) and finished for the time being, so I closed thunderbird and the PA-Menu, then did the "safely remove hardware" thing. When I returned to finish updating my "Sport" calendar, I accessed thunderbird throught the PA-Menu, but it displayed an unfriendly window: the licence agreement. I made a copy of the program on the computer in question and tried to recover my old data in some form, but the program was bare, and tried to install upon opening the *.exe which would still fruit nothing useful. I believe I have nothing to do except use my old backup, but please comment on this error if you are thinking that it might be of use, so that this problem can be fixed.