I want my videos back from September 15, 2021

Unless you have a backup that includes those lost videos, you can’t recover them. Having a backup that old is very unlikely unless you do not use automatic iCloud backups or you almost never backup. If you think you have a backup that is that old, you can restore it to recover the videos.

If you are syncing photos and videos with iCloud (using iCloud Photos) and you deleted them, they are gone for good.