Clean off your charger and port. Many times a computer will not charge because the charger/port is dusty.
Plug the computer into a different outlet and let the it charge for 5min turned off and then try turning it back on. If it turns on make sure you have all your Dell updates installed as not being up to date with these can lead to charging issues. If the Dell updates are all installed but the computer still seems like it is not charging run a troubleshooter on power:
Go into your settings and open Update & Security
Click on Troubleshoot and scroll down to find Power and run the troubleshooter. If you don’t see it click on Additional Troubleshooters
Click on "Power"
If the computer does not turn on OR still has charging issues after Dell updates are installed and the troubleshooter has been run try a Hard Reset.
How to do a Hard Reset
1) Turn off the computer or make sure it is turned off.
2) Disconnect the ac adapter or power cable from the computer.
3) Disconnect all devices like USB drives, printers, webcams, and media cards (SD/xD).
4) Press and hold the power button for 15-20 seconds to drain residual power.
5) Connect the ac adapter or power cable.
6) Turn on the computer.