A drive can fail in various ways, most of which will not harm your data and leave it fully recoverable.
- A bad write can mess up the partition table and make the drive unreadable. No data should be lost, though recovering it might be a hassle.
- A component failure (e.g. controller circuit) renders the drive unusable. No data should be lost, replacing the failed component fixes the issue.
- Head crash or some other catastrophic failure physically damages the platters. Your data is pretty much toast no matter what "CSI-forensic" lab you take it to.
Your best bet would probably be to take it to some recovery service and ask what they think can be done and how much it will cost.
- A bad write can mess up the partition table and make the drive unreadable. No data should be lost, though recovering it might be a hassle.
- A component failure (e.g. controller circuit) renders the drive unusable. No data should be lost, replacing the failed component fixes the issue.
- Head crash or some other catastrophic failure physically damages the platters. Your data is pretty much toast no matter what "CSI-forensic" lab you take it to.
Your best bet would probably be to take it to some recovery service and ask what they think can be done and how much it will cost.