text: how do you delete everything on ur computer so its like when u bought it? ? you need to have a basic grasp of dos. because no matter how much you re-format your drive, do disk clean-up and manually delete everything that you can, there are three .dat files stored in your computer that keep an ongoing record of every website you visit, every e-mail you send and receive and every chat that you participate in.  the .dat files are what the police and forensics use to retrieve information from people's computers who are suspected of crimes.  there's not enough room here to go into how to erase your .dat files but if you really, really need to get rid of some information google ".dat" and learn how.  good luck.