Sudo not working

sudo permission not working in /mnt directory
so i cant change owner group of my usb drive

actually i can’t copy/paste/delete/creat folder in my usb drive(root owner)
so i want to change it to me(user)

Welcome here!

Can you show exactly what commands you used, and what was the output? That will help a lot in solving the mystery.

For now the problem sounds like trying to change permissions of slightly wrong folder.