The other day my computer was freezing so I turned it off with the power button. When I pressed the power button again to turn it back on, the windows xp screen popped up but then a black screen appeared, saying windows couldn't set up successfully. I have tried all options several times like safe mode or loading windows normally but it doesn't work. What can I do?

A repair installation should help out here

Repair Installation
A Repair Install will replace the system files with the files on the XP CD used for the Repair Install. It will leave your applications and settings intact, but Windows updates will need to be reapplied.

Perform a Repair Installation (http://www.microsoft.com/windowsxp/using/helpandsupport/learnmore/tips/doug92.mspx)

Can you possibly borrow one from someone?

Give this a try

Start the System Restore tool at a command prompt
http://support.microsoft.com/kb/304449

Same happened to me a week and a half ago... hard drive crashed.

Managed to save info but had to purchase a new computer. And this time I also purchased a back up hard drive...

Stringer