Software wont restore backup

Not sure if anyone is familia with Microsoft Point of Sale but our computer recently crashed. The guy working on it took the hard out and connected it to his computer to extract the files. He got the backups off and loaded them onthe new computer. The software was installed on the new computer and he registered it but the backup wont restore. He cant figure out what is going on or why and I have no idea. Any clues? Also, when trying to retrieve a a newer backup he is getting a message that the database is not connected or missing (cant remember exact wording)
Any ideas or direction would be greatly appreciated
thanks!