software update

As described, the update process failed. If during boot an inconsistency or corruption is detected, you will see the restore screen.

You have no alternative other than to restore the iPad from your PC or Mac Computer. The full restore process will reinstall a fresh copy of the most recent version of iOS/iPadOS supported by the device. The restoration requires either a PC or Mac computer - to which you already have access.

At conclusion of the process, you can restore your data from either your iCloud or iTunes backup.

If you see the Restore screen on your iPhone, iPad, or iPod touch - Apple Support

Restore your iPhone, iPad or iPod touch from a backup – Apple Support

Hello donatella,

After restoring your device's system so it is working again you can restore it from a backup. Watch this video to see how:

https://www.youtube.com/watch?v=Jbp3gGTQygg

If you're still missing data this link may help regain it: About missing information after you restore your iPhone, iPad, or iPod touch with iCloud Backup - Apple Support

Connect your ipad into your computer

And click on Update