How do I undo my phone?
I accidentally restarted my phone. I logged back in through iCloud, but my phone is now the same as it was back then (4 years ago). All my photos are gone, and my apps and background are the same as they were back then. How do I undo everything?
I can’t. If you only have an ancient backup, you only get old data.
You can reload your apps through your Apple account. Everything else is gone.
Except you have a current backup somewhere, e.g. on the PC.