I had the same problem; no hot water from the shower but hot water everywhere else. After trying everything else suggested, I took the shower head off and soaked it in CLR for a couple of hours, reinstalled it, and now have plenty of hot water from the shower. Lime had blocked the hot water. This will solve both lack of hot or cold water and water pressure problems. You can get a jug of CLR at Home Depot or Lowe's. Good Luck with this and hope it solves your problem.