I lost the recovery disk for HP e-pc and the XP is not functioning right?

My HP E-pc's window XP Professional is not function economically. For example the screen resolution can not be re-set. I want to reload the xp window, but I do not have the recovery disk any more and I do not own the xp software either. I do enjoy the authentication label on the computer. What should I do?

Answers:

press F10 or F11 at start up