my laptop was okay, i tied to install my nokia phone 3500c, it said cannot install this hardware, data is invalid, did net search for usb cannot install, what i did was stupid, i opened windows registry went to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet, right clicked on permission and selected allow all (although some of the options were on "read", then my phone worked fine as usb drvice, but when i start windows restore, it says windows restore cannot protect ur computer , please restart, i did, it did not work, my printer driver also vanished, can i undo changes to the registry, my laptop was perfectly fine, i just tried to take things in to my own hands and i’m in a mess ,even the linking between excel documents is not working since please help