I don’t recall the exact error message, but sometime after an unclean shutdown your virtual machines will not start with an error that contains “unable to unlock file”. To resolve the issue simply navigate to the directory where your virtual machine resides, and delete all files with .WRITELOCK and .lck extension.That should remove the lock and make your VM’s accessible. If that didn’t help, go ahead and delete all files EXCEPT .vmdk AND .vmx EXTENSIONS. That should definitely do the trick.
You can actually delete the .vmx files as well but in order to have VMware recreate them you will have to start the “new virtual machine wizard” and use the .vmdk as your disk file. Instead of creating a disk you use an existing.