Another Problem!!

I flew my plane yesterday with an instructor. Ot was a VERY humid day 30 plus degrees. Nearing the end of the flight the engine stalled. My instructor said that everyone that day had experienced dead stiks. He also told me that he heard a pop sound when the engine gave up but noting came or poped off. He told me to start it just to make sure nothing was wrong. I emties the tank and tried to start it. It seemed the starter was slipping off the cone. I need to start it before rust starts to kick in from the moisture>