I have a 500 gb drive which was split into 2 partitions. Memory was all but used so have transferred everything onto a 1Tb external drive. I wanted to reformat the hard disk back to one partition and start from fresh. I managed to delete the D drive, but also somehow manage to convert the C drive to a simple drive. I cannot do anything with it now. A fresh install of windows 7 works, and although it looks like it is clean, the drive shows as still having 245gb used. I cannot find this data anywhere. How can I re format this drive properly?