If your SAMSUNG I337 Galaxy S4 is stuck or frozen, You can perform a soft reset operation. Check out how to force restart Android 4.2 Jelly Bean. As a result your SAMSUNG I337 Galaxy S4 should reboot and start running again.
Press Power button and wait for the menu in which select option turn off the phone, or pressand hold Power button and wait until the phone turns off.
Now press the Power button, and wait until the phone turns on.