oil pressure

I had and electreical problem and the truck would not fire, so it set for a period of months, i had that problem fixed. when i went and picked it up it had oil pressure but after about 5 mins. of driving it i lost all oil pressure if anyone has any suggestions emil me here or at jemikahancock@bellsouth.net thank you all for the help!!

oil pump most likely or the switch itself.  I would check it out very well before driving it, otherwise it could equal a new motor.  Could als be the gauge but I wouldnt take that risk of thinking its that.
 
Also the plug to the switch is possible, is it DEAD zero or does it have a little pressure?
 
Let me know what you find.