Things You'll Need
Instructions
Reset your Xbox 360. It doesn't have a reset button, so this can be done by powering the Xbox off, then turning it back on.
Ensure your Audio/Video cables are properly connected to the Xbox 360. If the cord has been partially removed, this can result in an E74 error. Ensuring that the cable is properly and completely connected minimizes this possibility.
Replace the Audio/Video cable. Unplug the old cable from both the Xbox 360 and your television. Plug in a new cord. If you continue to see the E74 problem, the issue lies in your hardware and must be shipped to Microsoft for repair.