althea, sounds like your BIOS password. You can reset it by following Dell's advise :"Reset the current CMOS settings:
Locate the 3-pin CMOS jumper (CLEAR CMOS) on the system board
Remove the jumper plug from the CMOS jumper (CLEAR CMOS) pins 2 and 3.
Place the jumper plug on the CMOS jumper (CLEAR CMOS) pins 1 and 2 and wait approximately five seconds.
Remove the jumper plug and replace it on the CMOS jumper (CLEAR CMOS) pins 2 and 3. "
The CMOS jumper is number 12 on the diagram