Most problems you experience with your Compaq Evo 310 can be solved rather easily. Even so, some problems require a more extensive approach and at times the only way to get the computer working again is to restore it to its factory default settings. If the operating system is corrupt or if the computer does not boot, restoring the factory settings might be the only way to restore the computer to health.
Locate the restore and operating system CDs that came with your Compaq Evo D310. Contact HP to order a restore CD set if you cannot find the one that shipped with your PC.
Connect an external hard drive to the Evo and back up all of your personal data. The restore CD process will format the hard drive and destroy your data.
Open the CD drive and place the restore CD in the tray. Close the tray and restart the computer. Watch the screen for the "Press any key to boot from CD" message, then press a key to force the Evo to boot from the restore CD.
Confirm the operating system you are using and continue the restore process. Click through the prompts warning you that the hard drive is about to be erased.
Insert the operating system CD when prompted. Enter the license key from the label located on the top of the Evo case.
Restart the computer when the restore process is complete. Connect the external hard drive and copy your personal files to the restored computer.