why do my high beams work but my low beams don't on my 1999 mazda B3000 truck

There is a high beam element and a low beam element in the light bulb both low beam elements could be bad.

thats right.. also high/low flash/light switches

I changed the bulbs on both sides and its still doesnt have low beams

Ok then its like Kelly said the switches he mentioned in his answer.

I changed the turn/wiper/high beam/flaher switch and still no low beams

ive been looking at this for you..start at work sheet 1. >http://www.autoshop101.com/forms/maz-ewd.pdf

Next step check fuses may be separate fuses for high beam and low beam.

there are 2 fuses...did you check the socket at the headlight for 12 volts with a test light.to make sure it not a ground problem.

I have a 1995 mazda b2300 the lights won't work but when I pull back my headlight switch the lights will come on?