Memory Full iPad 4th Gen

Okay, you just created a HUGE problem for yourself now.

As an aside FYI,

Once an iOS/iPadOS is installed, it never goes away.

An iPad will always keep the iOS/iPadOS version that was last installed on it!

Unless you have ever done any older backups of that iPad to a computer using an older version of iTunes, the only way to get back all the default iOS apps, including the Mail app is to do a complete erase and restore or restart of that iPad as a new device.

NOW, here is where all of the issues and problems now happen!

A complete erase and restore will make this iPad practically useless today.

Your over 8-year old, iPad 4th gen model is too old, now.

Apple ended support for 8-10 year old iPads, at least, over 3 years, ago.

Virtually, ALL third party iOS app developers ended/stopped/abandoned supporting these old iPads over two years, ago.

There are virtually, NO MORE older iOS 9 or 10 compatible apps available from the Apple iOS App Store, any longer.

You will never get anymore older, third party apps from the iOS App Store, any longer after this iPad model has been reset.

The internal hardware in that iPad is too old, too underpowred and completely incompatible with all later versions of iOS/iPadOS, too!

Simply put, your 4th gen iPad is too old and obsolete now.

There is nothing to be done.

This iPad is done with no way to get apps to continue its functionality.

Sorry & Best of Luck to You!