You may have run the battery flat.
That puts the chip inside the battery into a "coma." Leave it plugged in for a few hours and don't interrupt the cycle by pushing buttons or disconnecting the charger. It will "wake up" and show about 3-5% and then start charging normally. Let it charge to 100% before disconnecting from charger and then resume normal operations.
If you need additional help or have more questions or details to share, please join the site so you can reply in this thread. See
this link for instructions on how to join Windows Central.