We need a little more information in order to help you. For example, what model do you have? Is there any response from the system? Backlight on the display? LED light on the CAPS lock key? Chime on startup? Does the charger make a noise when connected? First try doing an [link|https://support.apple.com/en-us/HT201295|SMC reset|new_window=true] or a [link|https://support.apple.com/en-us/HT204063|NVRAM reset|new_window=true]. If those don't work, you'll need to consider opening it up to try to diagnose the problem internally. You could try disconnecting and reconnecting the battery. Good luck!