|Format your driver? Do you mean you tried to format your hard drive? |
You can't format your system drive from within Windows which I suspect you are trying to do.
If you really want to start fresh and wipe out all data on your drive, put the Windows disc in and boot to that, then you will have the option to partition and format your drive. Be careful though, doing so will wipe you drive and you will loose all your data, programs, etc.