Installed Windows XP - Erased everything??

I know nothing about computers so you will have to forgive me, but my laptop recently went haywire and kept rebooting itself so I installed Windows XP Professional (I previously had Windows XP) and now my laptop seems back to normal except I cannot see any of my documents, applications or music....Did I just completely erase my harddrive by installing XP Professional???? I am dreading the answer... If somehow I did not, please let me know how I might find my harddrive data!! Thankyou soooo much for your help!!

Newbie

But I never formatted the disk. I actually just reinstalled a Windows XP Professional that I had from my PC to the laptop. So I don't know how to activate my laptop now as the Activation Key was already used for the PC.

Unless it gave you an option to leave the file system intact and you took it, you can't install XP without a format, to my knowledge. Unless what you're saying is you repaired windows instead of reinstalling it...that's completely different.