Hi @1annabel Have you searched in My Files as well as Google photos? Do you have syncronisation with One Drive set up or do you use any other service such as Dropbox? Information on some services here. Will be problematic without backups and I would recommend using both Cloud services and local storage. Some information here https://www.findingtheuniverse.com/photo-backup/
However that may be more of a safeguard for the future. If you cannot locate anywhere you might be able to recover using Data Recovery software but no guarantee. I cannot recommend any one myself as have not needed this option but you see some information here https://geekflare.com/android-data-recovery/
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
My Device- S21 Ultra 5G ( SM-998B/DS ) CSC= BTU , 12GB/256GB
One Ui 5.0,Android 13 .