Hi Druw2126,
We'll need a bit more information so that we can provide the most accurate steps to help. Is your iPhone unresponsive? If so, then force restarting it will help. Here's how: Force restart iPhone.
Force restart iPhone
If iPhone isn’t responding, and you can’t turn it off then on, try forcing it to restart.
1. Press and quickly release the volume up button.
2. Press and quickly release the volume down button.
3. Press and hold the side button.
4. When the Apple logo appears, release the side button.
It also sounds like you may have been attempting to reduce the size of your iCloud backup by turning off iCloud backup for the Messages app with the steps from this article: Manage your iCloud storage.
Reply with the answers to these questions so we can help further:
- Do you no longer want to turn off and delete iCloud Backup for the Messages app?
- What steps are you taking to "undo" the process?
- Does simply restarting your iPhone allow you to switch the Messages app back on in the Backup settings?
Cheers.