I tried to open the two password safe databases I have and both have vanished. Search can't find them. Have I been hacked and if so do I need to change all my passwords?
Unless they know your passphrase, they should not be able to open them if they had them. Obviously, the stronger the passphrase and the less guessable they are the better.
Ca't say that from this amount of information....
What version of PasswordSafe are you using?
What operating system are you running on your PC?
Are there any other files in the directory in which you normally keep your databases? There may be ones with extensions 'bak' or 'ibak'. If they exist, save a copy elsewhere (just in case) and these can be opened with PasswordSafe as they are databases in their own right.
Of course i forgot - you have backups of your databases don't you?
If it is that important to you, then surely you take reqular copies (e.g. to a USB stick) and store that somewhere safe?
Files can get corrupted - not just PasswordSafe's but any file. Hard disks do fail (they are mechanical and if a thing moves - it can break). So of course you have a backup.
Just restore the latest backup and you are back in business.