ABS light traction control light and check engine light are on

It just started over the weekend, the ABS and traction control light started coming on, the lights go off occasionally and stay off. Then they come back on, I can stop just fine, when I got the car was told that they didn't know why the traction control didn't work, car sat up for a little while. I need my car. What could be the problem and how can I fix it without it costing me an arm and a leg? Have had the car for almost three month without this happening, I am worried it's something major.