How to change screen Resolution back?

i enlarged my screen and it went blank there is nothing cant see mouse moving in order to change it backHow to change screen Resolution back?
If it didn't restore on its own, do this:

Tap the power key on your PC and allow it to shutdown.

Restart your PC but tap F8 (function key) to display the startup options

When the options appear, select ';safe mode';

At the login prompt, login

Either do 'right click' on screen and select properties %26gt; 'settings' - or -

'control panel %26gt; display %26gt; settings'

Reset your resolution to 800x600 @ 60hz.

reboot normal.How to change screen Resolution back?
restart PC during the boot hit F-5 or F-8 choose safe mode then go into control panel display change and restart