Help please!!! Screw won't loosen?
Is this screw part of a furniture assembly?  What you describe sounded like a cam-lock nut, like can be seen here: http://www.swedishfurnitureparts.com/products/ikea-cam-lock-nut-103433
If that's it, then it won't actually retract, you just align it so the adjacent part can be removed.  There should be a dot or indicator showing you which way it needs to be aligned.