87 ford ranger starter ???

have a 87 ranger, was running and driving just fine , then it died and when I went to restart it, the starter just spun, motor would not turn....replaced the starter and the relay with new parts, and my problem is still there. my question is.....what is wrong...anyone know, please any help would be great thanks!
marvin

Chipped teeth opn the fly wheel??? if it is all you would have to do to check this is to trun the crank a few inches and try starting then.