You'll need to run chkdsk with the repair flag.
chkdsk <drive letter> /f /r
It will attempt to repair the possibly damaged sectors. If it can't repair them...then the drive isn't looking good and you'll have to try and recover data off of it some way.
Usually Windows has issues reading dying drives, so I would suggest that if you can't access the drive in Windows after running the chkdsk repair, then create a Linux LiveCD or LiveUSB (such as Ubuntu), boot off of it, and access the drive through Linux. I've had much greater luck accessing dying drives that way than through Windows.