If your program was working but seems to no longer run, or if your computer went to sleep and your program no longer responds, try resetting the software using the following procedure:
Save your work.
Close the programming software you’re using. Note that you do not typically need to close Scratch or Snap!, but you will need to quit out of the BirdBrain Robot Server or the CREATE Lab Visual Programmer.
Disconnect the Hummingbird from USB AND from Motor Power.
Reconnect the Hummingbird to USB and then to Motor Power.
Reopen the BirdBrain Robot Server or CREATE Lab Visual Programmer
Re-run your program. If it works, then the issue was probably a software glitch.