Well, it didn't go back inside by itself. I called around to several vets and finally found one who sounded as if he might know something about reptiles. Of course, it happened at the beginning of a weekend and I couldn't go in until Monday morning. The vet didn't seem as knowledgeable in person as he seemed on the phone, but he was all I had. I didn't notice until I put the turtle in a tupperware box with a damp paper towel in the bottom that he was bleeding. Anyway the vet manipulated it back inside with sedation and lubrication and put a circular stitch in to keep the penis inside. The stitch is due to come out in a couple days. I was unable to get much antibiotic in him without stressing him out too much, but he seems to be doing okay. His tail seems a little stiff. He seemed sort of sluggish and I was worried for a while because he didn't jump at the worms I gave him, but he gobbled up all the fairy shrimp I put in the tank. Hopefully he can breed when his female gets a little larger. It cost me about a hundred bucks- plus mileage.