If it is formattable...
Format it with HDD Low Level Format Tool software.
If it's unformattable, or you have some data, you cannot afford to loose...
Recover files from software like Power Data Recovery, Recover My Files... but use Recovery option like normal or advance recovery (not the format or extended format recovery)...
If doesn't work, or you have any other question, just ask. In my opinion, it will work.