headlights acting up?

my lights have been working fine, then recently, they wont turn on. im thinking the switch because when i pull it all the way back, just my yellow corner lights go on, and the only way i can get the lights to go on is to pull back on the brights lever (allll the way back, and then all of my lights will go on, including the brights) so i kno its not the bulbs. is it just the switch? what should i check? its getting annoying having to hold back the lever to drive at night