While some people return their computers to its original factory settings to clean out unused programs and files, the most common reason for restoring your Dell Dimension E520 computer to its original factory settings is a corruption in your operating system. Even the most novice computer user can complete this task.
Insert the operating system installation disc into your CD drive and restart the computer.
Press any key on your keyboard when the computer prompts you to press a key to boot from the disc drive.
Choose the restore option when the computer requests that you choose to either repair or restore your system. This will remove all files and programs from your computer while returning it to its original factory settings. The restore process will continue without further prompting from you and will restart the computer when it is complete.