Problems in restore backups to iPhone from PC

My dad wanted me to update his iPhone X to iOS 14, so I tried to, and iTunes in the PC gave some error about connecting to the iPhone (unfortunately I don't have the exact message error), so then I went to my Mac and updated his iPhone from there. Now I can't restore his iPhone from backup (from the PC), due to "read and write" error. I have checked the access privilege to the backups folder and discovered it was empty! iTunes says that the iPhone was backed up. I would have checked if his iPhone was backed up on my Mac, but I went back to my apartment. Any thoughts on how to restore from backup (or how to check if its a lost cause)?