I sort of feel sorry for the OP. Here he is with a problem and we're all taking it as a straight line.
To the OP, don't post straight lines when there's a full moon.
Otherwise, See my earlier post No.2 or 3 for the general answer. Or you might get more specific help if you post more detailed info. Ie. is a cassette or freewheel, is the chain turning, but slipping on the sprockets, or is the rear sprocket turning but not driving the wheel?
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