Sounds like you need a new mechanic.

If there is no compression(I guess that is what you mean), it would most likely be on one or two cylinders, and be a ring or valve problem. If it turns over when you turn the key, and does not make any bad noises(from twisted metal scraping on other metal), I would be surprised if your mechanic is telling you the truth. It is relatively straightforward to check out the ignition system, you should probably do this,