Having this issue when you find your laptop is not charging can be quite frustrating, for a moment you might feel lost, and have no idea about what to do, real issue is when you plug your charging cable to your laptop and still it tells you not charging, or plugged not charging.
However you can fix this issue, first of all you should try reconnecting your AC adapter to your Laptops for students and see if it works, reconnect the battery, turn your laptop off and turn it on and see if it works.
Second thing you can do is try using wall socket, sometimes it happens that AC adapter stops functioning properly, you can check it by doing so.
Dell Laptop Plugged In Not Charging
Another important thing is to change the AC adapter, if it is possible for you, if you have 2 adapters or by any means you can check this through your different adapter then it would be best option, as you can figure out if your adapter is out of order.
Also you can check your battery charging driver; this is least but still one of the possible solutions, as you might not know if your drivers are outdated or corrupted somehow, if nothing is working then this should work for you.
You can go to device manager and check the drivers, and also you can use different application that automatically suggest you the drivers.
Hope this will help you figure out why your laptop is not charging, and in most cases it just works after taking care of AC adapter wire, make sure they all are firmly attached, you should not loosely attach them, this might interrupt charging and it can even cause spark which is not good for both laptop and AC power adapter.