1. When you start the car does it go on an off. If not. Bulb is broken or taken out SO......
2. Find a straight section of road thats quiet, drive at 40mph and slam the brakes on, if you skid and the pedal doesnt vibrate, someone has taken the bulb out or broken it, as the abs is not working.
(this is commen, as they get faults all the time, so peopel cheat to sell it)
Probably only a broken sensor to fix IF its broken, about £17 for a sensor from GSF online.

Hope that helps, any queiries just ask
