How do I get back my pictures that I lost

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

Permanently deleted photos can't be recovered from recently deleted after 30 days Delete and recover photos and videos on iCloud.com - Apple Support

In case if you had backed up on an external drive using Mac then there is a possibility .