This scenario and question is asked several times a week . . .
Reset it. If you have a Clip (original) hold the sliding power switch on the side in the uppermost position for 20-30 seconds. Don’t guess; count it out (one mississippi, two mississippi, etc.), or use a clock.
With the Clip+ press and hold the power button for the same amount of time. It should now start up and run normally.
