I updated my phone and in the process it permanently deleted some photos. How do I get them back?

If you're missing photos or videos in the Photos app on a mobile device, read this support article --> If you're missing photos or videos in the Photos app - Apple Support

Things to do:

- Check your Recently Deleted folder - Go to Photos > Albums, and tap Recently Deleted in the Utilities section.

- Make sure that iCloud Photos is turned on

- Sign in with the same Apple ID

- Unhide your photos

In what view did you notice photos were missing? If it was you My Photo Stream then you didn't lose any photos. The My Photo Stream just readjusted itself and lists only the last 30 days of photos.

If it's not MPS then have view did you expect to see them in and are they new or old photos?