mouse problems

I have replaced my video card a cd/rom/dvd and my secondary hard drive on the computer and added 128mgb ram card. It is a athlon 800 and os windows xp

All was fine till I started - and don't ask me why- to install hardware i.e hit the add hardware button assuming that this is how I am installing the new hard drive.

what happened next is indescribable. somehow the hardware detector re-installed all sorts of drives that were already installed and they appear in device manager with yellow triangulars. Also I can't initialize the new hard drive.

The worst problem is that the mouse stopped working. Nada, dead to the world although it says that the device is working properly.

I am not a professional and just work intuitively with my comp and I am well pissed off since I don't know how to use keyboard to replace mouse and get into muddles.

Any idea what I have done, anyone ???