I have a emachine never got a reboot disc can you tell me how to reboot to factory settings clean everything out at once

Rebooting is just restarting the PC without totally shutting down. What you obviously want is to reinstall to factory defaults. If your hard drive has a hidden restore partition there is usually a key to press during start-up to initiate it. Watch carefully, usually at the bottom of the window, for instructions for what key to press. It could be called restore but would not be system settings. If you Google your machines brand name and model number followed by the words "Factory Reset" and look for a link to the emachines website, I suspect they will point you in the right direction.

F9 and F11 are typical but not inclusive