Actually I found the answer to the question right in the User manual that was right in my car. Took me all of 2 mins to change the bulb. Actually the instructions on how to do this are in the owners manual. If you don't have the manual, all you have to do is remove the headlight assembly by pulling up on the two plastic retainers then remove the rubber boot and the bulbs are exposed. Turn the bulb one quarter turn to remove.
Took me all of 2 mins to fix it.
I had the same problem with my 98 buick regal gs and it turned out to be the ignition switch.
http://www.automotivehelper.com/topic1054152.htm or Goole "ignition switch replacement 2001 regal"
where is temperature switch on 1996 buick regal
Check out this link. It includes pictures. I am certain your 2000 Regal will be very similar if not identical to the 2001. http://www.clubgp.com/cgi-asp/mods.asp?modid=141
were can i locate and replace a starter for a 1998 buick regal?
How do you replace the morror assembly for a 2001 Buick Regal
How do you replace the fuel filter on a 2003 Buick Regal?
how to replace a radiator in a 1996 buick regal
You have to get it from a Buick dealer.
Flasher is bad. to replace it it is under the dash at the back of the steering column.
how to replace master cylinder on 1996 buick regal
Pull the turn signal stalk towards you to activate your high/low beams