Try running firefox from the commandline, what happens? If that fails, try running the following from the command line:
Try removing your profile (you will lose your bookmarks, passwords, browsing history, etc). Your profile is usually located in ~/.mozilla or ~/.firefox, it's a sub-directory in there, remove the subdir only.
This is a fixable problem (or at least should be). The issue is figuring out why firefox isn't starting. That said, it's possible that firefox not starting is the least of your problems. Who knows what else is busted. . . getting some idea as to why firefox is failing may help you figure out if anything else is broken.
If all else fails:
- Create a new VM
- Install OS on new VM
- Add disk image from the crashed VM to the new VM (add disk via vmware settings)
- Copy needed data from old disk, to new disk.