If the battery has become completely discharged for any length of time, then it can be difficult or impossible to charge the battery and the battery could be permanently damaged. When this happens it can prevent the laptop from powering on because power is actually pulled from the battery even when using the charger.
Try an SMC reset.
Let the laptop charge for a full day to see if the battery can actually begin charging again.
If you have a Touchbar model, then try connecting the charger to the other side of the laptop.
Here are Apple articles for troubleshooting charging issues:
USB-C charging troubleshooting
Magsafe charging troubleshooting
FYI, when storing a laptop you need to make sure the battery is charged to about 50%, then power the laptop completely off (full shutdown) to minimize the draining of the battery. See this Apple article for details:
https://www.apple.com/batteries/maximizing-performance/
If these things don't help, then you will need to have Apple or an AASP repair your laptop (make sure to take along your charger and charging cables).