I had a friend of mine replace the front struts, now the ABS light is on.

this is the trouble when someone does you a favor that saves you money. he most likely damaged the sensors during the repair and now you need sensors. always let a shop perform these repairs. it is well worth it. Roy

Its easy to damage the the ABS sensor cables that go out to the sensors. The cables are delicate stretching them cam damage the cable requiring sensor replacement (quite expensive too).