1994 Honda Civic timing belt

Hi, I have a 1994 honda civic dx. The timing belt went and my mechanic told me that the valves bent do to the belt breakage. He purchased a used head and replaced the old one with the timing belt. Then, he replaced the water pump, the oil pump and gaskets. The car still won't run. He keeps saying that the timing is skipping a gear or two. He claims every time he has to adjust the belt he has to tear it all down to get to it. I need to know if this is true my car has been at the shop for almost 4 months I cannot afford to take it some where else. Please explain just how a belt is changed what is involved in it and is there something else I should now about this. I am disabled and I need my car I cannot take a bus and cannot afford a cab. Any information to help me better understand the mechanics involved in changing this would be well appreciated. I am a very knowlegdable person so I will understand if you explain it to me. Thank you, Hooprock324