Why does my computer no longer recognize my all-in-one printer?

I recently came home to discover an unnamed person in the house-hold had ruined my HP Deskjet 4100 series all-in-one printer. He says he doesn't know how he did it, and I have not been able to figure it out. I have uninstalled and reinstalled the software numerous times. I don't have access to the original software because the diskdrive no longer works as well. Something unholy is happening here. I am running Windows XP service pack 3. Don't really know what other info you need. Oh, the printing and coping portions work just not the scanning. It used to work wonderfully. Not sure how the scanner won't work but the copier will considering they use the same components. Please Help.