In the event of problems with a hard drive, you are always flirting with data loss. Here are a few simple rules to determine what your next step should be:
Scenario 1: You hear a drive making unusual clicking and/or grinding noises. Steps to take: Stop using the drive immediately. Whenever a drive produces these kinds of sounds, you’re risking that the heads are scraping over the platters (called “scoring”) which will make it impossible to read any data off the drive. Call the Data Rescue Center immediately!
Scenario 2: A drive is no longer recognized by the computer and doesn’t show up on the computer at all or only very intermittently. The motor inside the drive is spinning, however, and does not produce and unusual sounds. Steps to take: Very likely a failure of the drive’s electronics, however the data can usually be fully recovered. Any drive that does not show up at all on a computer despite seemingly working fine can typically not be recovered by the user. Please call the Data Rescue Center for a free evaluation of the drive.
Scenario 3: A drive is showing unreliable behavior. It occasionally seems to freeze when accessing data, but does get recognized properly by the computer. Steps to take: In a situation where a drive shows some inexplicable, seemingly random behavior, this points to the drive having many bad blocks or a weakness of one or more of the read/write heads. You should copy important data off this drive ASAP and replace the drive.
Scenario 4: Data has been accidentally deleted from the drive, or the drive has been formatted or partitioned by mistake, causing data stored previously on this drive to be gone. Steps to take: Do not write any new data to this drive, as this will make a full recovery impossible. All these actions mentioned have so far only affected the Table Of Contents on the drive, the actual data is still there and can be recovered with a software package like Data Rescue. By not allowing any new data being written to the drive you prevent that your old data is being overwritten and gone for good, because once new data is written over your data, it can never be brought back.