Data recovery cannot be completed. Please restore your iphone from backup.

This explains how to restore a backup. There are instructions for using iCloud and iTunes.

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

If the screen does not respond, or stays blank/white, you can try recovery mode.

If you can't update or restore your iPhone, iPad, or iPod touch - Apple Support

krissie34 wrote:

I plug my iPhone into my computer to back it up through iTunes but because my phone is stuck on that white screen, I cannot accept the access to let it connect to my computer.

Im not sure how i can backup my iphone if i cannot connect it to my computer.

You can’t back it up now as the message is telling you. You need to restore a backup, if that’s possible.