I have just (yesterday morning) changed the oil & filter and the
thermostat and everything seemed to run fine, then at night I was
driving to work and the headlights, panel lights, brake lights and
radio went out. I turned the hazzard lights on and finish my way to
work. This morning I checked the fuses and everything seems to be fine
there, I made sure they were all in tight and not blown, so I tried the
lights again, this time the radio is working, the brake lights are
working, but as soon as I switch the headlights on, everything stops
working... My daytime running lights are working though...
There is a little oil leaking, I am going to check that out today and
the thermostat seems to be tight, (it didn't come with a gasket, not
sure if that is normal or not) do either of these things have anything
to do with the lights? Also, the reason for the thermostat change was
that there was no air blowing out of the vents and the guy I bought the
car from said the heater core was previously change (not sure if it
was, cause now I still only get very little heat, but more than before)
My dad tells me girls shouldn't be working on cars, but I don't think
that is it either... lol

Any help with any of these problems is greatly appreciated

check battery cables to be sure they are clean and shiny

http://www.minibite.com/america/malone.htm