Help! My iPad has gone really weird.

Start with a forced-restart of your iPad:

• On an iPad with a Home button: Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.
• On an iPad with Face ID: Press and quickly release the volume up button, press and quickly release the volume down button, then press and hold the top button. When the Apple logo appears, release the button.

If your iPad doesn’t turn on, or if it gets stuck during start up, see the Apple Support article If your iPhone, iPad, or iPod touch won’t turn on or is frozen.

If this hasn’t resolved the problem, the next step is a Settings Reset:

Settings > General > Reset > Reset All Settings (this reset is non destructive - you will not lose any data)

If no improvement is seen, a full reset of the iPad might be attempted:

Settings > General > Reset > Erase All Content and Settings (this reset will wipe all data and installed Apps)

If the problem persists, a Factory Restore is advised - for which you will require a PC or Mac computer. This procedure will (re)install the most recent version of iOS/iPadOS that is supported by your iPad:

Restore your iPhone, iPad or iPod to factory settings – Apple Support

If you have followed all of the above advice - and followed the linked procedures - what did Apple Support have to say when you contacted them?

If your iPad is within warranty, you might be best advised to contact your retailer and pursue repair/replacement.