i would like to ask what's the best thing do when your computer asks you to reformat the hooked up HDD. So what happened was, my husband accidentally drop the HDD probably 4 inches high. when we hooked up the hdd again, it would not display any of the files we saved on it and gave us the error message saying: the disk has been formatted, would like to reformat now? so, we didnt reformat fearing that we cant recover our files. what should we do from here?
You are right NOT to Format the drive. That would certainly make recovering files from it much more difficult.
The drive is malfunctioning in some way, perhaps related to the drop. It may be as simple as the power or data cables to it were loosened and need to be re-connected securely. If this is an external drive in a case, the connections between the actual HDD unit and the case electronics could be loose. Or, the case electronics could have a flaw even though the HDD itself is OK.
There are many steps to isolating the cause of a malfunctioning drive. There have been lots of threads on the topic here. Try reading through some to see if you get ideas on how to proceed. One good way to start is to mount the HDD inside a desktop machine and use a set of diagnostic utilities (download for free from the HDD maker's website) to test for hardware problems.