|"how can i turn it on"|
You mean brightness?
Did you try Google? If you give me the make and model number I can try but there's no real reason why I will do any better. Every computer is different.
You access Display Properties by right clicking the desktop and choosing Properties from the list, but brightness is not a normal "Windows" feature.
If you mean System Restore then here is the info for XP:
Always pop back and let us know the outcome - thanks