Recovering deleted photos and videos on iPhone

Did you check the recently deleted folder in the photos app?

If they are not there, restore them from your backup.

If they were not backed up or stored elsewhere, and are no longer in the recently deleted folder, they are gone. there is no place else to recover them from.

What were you doing when this "mistake" occurred? How were you managing your photos? Were you using iCloud? Have you checked your Recently Deleted folder in Photos? Do you have a recent backup of the phone?