Do you mean that you want to set the OS back to the way it was or reset the BIOS to the way that was. To deal with the latter first, if you go into the BIO, you will find a option to reset to factory settings; alternatively you can remove the small battery on the motherboard a return it after about 30 minutes. But this will not necesarily be as you first recieved the PC if the builder amended the original settings. So far as a software reset is concerned, you will need either the original software or a system restore CD, either of which should have been supplied when your bought the PC. If they never gave you one, and some companies cut corners in this way, then there's nothing you can do apart from trying to get them to supply one under warranty or extra payment.