I’ve done everything suggested to charge the battery on my IPad, but it doesn’t charge

If the iPad won't charge after you have followed all the instructions in the Related Article above your post, then you need to contact Apple Support. Use the Get Support link at the top of the page here or if you have an Apple Store close by, make a Genius Bar appointment to have the device checked. Genius Bar Reservation and Apple Support Options - Apple

Make an appointment at the nearest Apple location to have your iPad evaluated for free.

Once the diagnostics are complete, the staff will explain your options.

Make a Genius Bar Reservation

Genius Bar Reservation and Apple Support Options - Apple