My phone has stopped backing up

Hello Jodywild!

It could be that there's not enough iCloud storage.

Or is the iCloud Backup option is greyed out?

You will find answers to these problems and more by clicking on the following link:

If you can't back up to iCloud - Apple Support

If you still need help, then please contact Apple Support.

I hope this is helpful. Good Luck!

Try a Forced Restart, it resolves many issues:

Force restart iPhone - Apple Support