If you have a brand name PC [Compaq, IBM etc], then chanes are you will have
a set of CDs entitled System Recovery. These can be used to 'reimage' or
rebuild the Hard Drive to the original state as shipped from the factory.
It will overwrite your hard drive with the image that is one the CDs, you
will loose everything on your hard disk, even if you have made partitions
etc. as the restore process obliterates everything you have done.
If you have an OEM version of WIndows, or a Full Retail Version you can use
the Windows Installation CD to reinstall Windows. This can be a repair
install, which preserves all your settings, documents and applications that
have been created since first starting the computer. It can be a clean
install, which reinstall Windows and wipes out everything.
