Compaq Presario 5000 5372EA - how to?

Hello,

Would like to know how to perform a full system restore, to return everything to its original settings as the computer is endlessly telling me that i have no disk space left on the C drive, even when i delete items from the C drive the space goes up but then rapidly disappears again, hence why i would like to perform a system restore, but i don't quite know how. This happens on a daily basis, i have recovered files that i want to keep so answers please.