Ursprünglicher Beitrag von: Dan ,
Reconnect it to your Mac then launch Disk Utility does the drive show up under it? If it does run Disk First-Aid to see if it can fix the corruption. If you can't see the drive with Disk Utility or it can't fix it the drive has gone bad. Hopefully you have a backup, if not you might be able to get a data recovery service to recover your stuff but it's expensive!