There is a code for the radio in the Honda Accord that is usually four digits long. This code is used to keep the radio from being used by anyone who does not have the code. If the code is entered incorrectly too many times, the radio will become locked and will require a new code to be entered. The code is usually located in the owner's manual or can be obtained from a Honda dealer.
If the answers above didn't work then you should also try:
- Check the radio fuse
- Check the wiring harness
- Check the radio ground wire
- Replace the radio