You can see this:
If you're missing photos or videos in the Photos app - Apple Support
Basically the above says to look in Recently Deleted and in Hidden. Be sure to check your Library thoroughly-- the pictures may not be where you expect, as dates may have changed. You can use the search field with the date or location. And remember, you can sort the Library by date captured or by date added. Also, your Library view now has filters, and you may not have your filter set to "All Items:"
If you use iCloud Photos, you can look at Photos in iCloud.com This can serve as a backup if your phone is lost or crushed, but not for when you used Photos' delete functions.
If you don't use iCloud Photos, but you have Settings>Apple ID>iCloud Backup turned on, then you may be able to recover data from the last 30 days or so at iCloud.com, but you would need to look at the date of the backup to be sure it's from before you lost the images. You should look here:
View and manage iCloud device backups - Apple Support
This requires you to erase everything on your phone and replace it with the backup.
You could try calling Apple, but you should not expect that to be very helpful.
If you don't keep your own backups on an external drive, then there really isn't any place else to look.
