Can someone please give me some advice? I have a 45rpm of "I THANK YOU" autographed by J.O'K in its original cover. Any idea how much this is worth?

You might put it on Ebay and see what you get offered or, call a couple of collector stores and see how much they think it is worth.

A search on google may also produce results. The worth could be in the signature, not so much the record, although that still doies have value.