Errors message shows in Hard Drives.

I am using a 320 GB Samsung SATA hard drive for my desktop PC. I used it for the last two years. Recently it shows me a problem when I am using it. When I want to open a drive in the computer it shows, "The drive is not formatted. Do you want to format it now?"
After clicking on the OK button it says format completed. But when I want to reopen this, then same problems happen again and again. What can I do now?

