So for this error treatment, you really don’t need to get depressed, because “Plugged in not charging” is a same old Windows OS Error and sometimes can be fixed, quickly as a wink.
Generally, the problem is coming from the OS side, but if you are really running out of your luck. Then it’s surely possible that the problem relates to some major hardware and you’ll have to send your laptop to the repair shop.
While you can also buy Original 65W Asus X751LJ-TY033T AC Adapter Charger + Free Cord,