Repairs Craftsmans 19 HP B&S won't turn over even with the spark plug removed

I have a 2014 Craftsman lawn tractor with a 19 HP B&S engine. It was running fine, but would not start after turning it off this week. I thought it might be the battery, but it was fine. I looked at the valve rocker and things seem to be working right there. The thing is, it won't turn over, even with the spark plug out. I can turn the engine over with a wrench about 45 degrees, but that's it. Any ideas? Thanks.

I solved my own problem. The exhaust valve was stuck. I got valve unstuck and the engine would rotate freely. As far as I could tell, there was no valve or push rod damage. I reassembled the engine and it started right up.