Reformat the computer. It will erase EVERYTHING though. so if you have an external hard drive, back everything up in there. But reformatting will erase your operating system as well. lets say you have windows xp. if you reformat, your computer wont be a Windows XP unless you install it. This will remove all viruses and your computer will be fast again. Be sure to get a good antivirus and antispyware softares right after you reformat so that its safe.
Reformat the hard drive. When you initially turn on the computer enter the boot menu, change the boot sequence to have the CD ROM boot first rather then the Hardrive. Insert Operating system disk and follow the instructions.
If your computer is manufactured one like DELL/Compaq/HP/Gateway, your computer may have come with a system restore disk that will do the reformat for you and install everything exactly as it was when you brought it home. If it doesn't come with this disc, many tiimes you can buy it from the manufacturer.
You can use programs such as Active@ KillDisk found at www.killdisk.com These programs are available incase ou don't have a Operating System disk available or you are throwing your hard drive away and don't want your data out there possibly ing the wrong hands.
If your computer is an Acer, there is an option using Acer eRecovery Service to restore it to the Factory Default. Your Acer may also have come with a revocery disk, which you can restore using using the eRevocery Service.
Boot n Nuke is a free software disk that can format and erase your hardrie over and over again. Running it 30 times (asked how may time at menu) is a safe way to know that everything that was ever on there is gone. Thirty plus is military standard.
1.Goto www.dban.org2.Click "Download"3.Click "for CD and DVD media"4.Burn the downloaded file to CD/DVD with iso burning software like infrarecorder which is free to download at http://infrarecorder.org/.5.Insert the disc and reboot the machine.6.If your PC is set to download from drive first which most machines are. if not press F8 or F12 then select DVD drive.7.Your PC should load the disc and then follow the instructions on the screen.
Formatting may take some time but it is well worth it because it erases data a few times to a standard where no data is recoverable.
Restart your comp. Rapidly press F8, F10, F12, or F2. A screen should come up asking questions..
Choose "Full factory recovery".. that's it.
By the way, get some discs and burn your most important files to a CD.
Go to Control Panel->Add/Remove programs. Then uninstall all the softwares
You can go to the control pannel and system restore then you can set your computer's intformation back to the date you want to.