If your computer isn’t charging, first, clean off your charger and charging port and try plugging it into a different outlet. Many times a computer won’t charge simply because of a dusty charger or bad outlet.
If that doesn’t fix the issue do a power troubleshoot.
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"
After this check to make sure all your Dell updates are installed. Not having these often causes charging issues and may be the source of the problem even if some issues are fixed with the troubleshooter. If all else fails a hard reset will sometimes fix charging problems. Follow these steps to preform a hard reset:
1) Turn off the computer.
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.