my car cuts off while driving. it turns over now but will not start.

Ok so I called the mechanic and he said he did order the new relay and tried it but it still would not start.. currently my car is still there at his shop. I have been searching over and over on google to try and find an answer. I guess I am probably going to have to have it towed to another shop that can hook it up to a computer and maybe they can figure out whats wrong..I did read somewhere that the problem could also be the ignition switch. I appreciate that you have been here to help me with this. I am stressed out over my car.