Your hard drive manufacturer should have a downloadable application. Check their website. They are designed for this very thing. You can also go to start-->run-->chkdsk /r <--this will schedule a chkdsk for the next time you restart, scan for any errors, and try to repair any it finds.
Better to first (download, burn and boot to a CD of, and) run the manufacturer's drive diagnostics, because in addition to repairing problems with the drive, CHKDSK /r will also perform it's proper and primary function, that of finding and fixing problems with the file system, which can cause very serious harm to one's data.
I know this firsthand; a number of times I've had drives pass drive diagnostics, but have file system errors, and after running CHKDSK most of the data has been lost. (Fortunately, in each case I knew to make a copy of the data before I ran CHKDSK.) CHKDSK can be so damaging that I know (otherwise) sophisticated users who refuse to use it even when it is appropriate to do so, because they never forget the major trauma it can inflict upon data.