OK Joyce

Lets start at the root of the Computer, can you switch off all power and disconnect the power cable from the back of the Computer and leave it disconnected for a full 45mins when you do this press the on button "this will drain any power left in the system to the LEDs / Fans", then remove the Motherboard battery (and please do follow ESD - "Electro Static Discharge" guide lines, leave the battery out for 15mins.
When the time is up power up the Computer and check your hardware is showing in BIOS if all is showing try the XP disk from boot again.

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