Hello Asusweary
Can you please elaborate if it is only the @ button that is typing the wrong characters or other keys of the keyboard have the same issue?
This issue can be because of any of the two reasons.
1) The Fn key on your laptop's keyboard is locked.
2) The keyboard layout/input language has been changed.
Can you please tell the exact model of your ASUS laptop? This would help in giving you the exact solution as how to unlock the Fn key either from BIOS or by pressing any toggle key(s). Also, in some laptop models, there is no Fn locking system at all.
In case you are not sure what to do or don't want to dive into the BIOS configuration stuff, you can check if the keyboard layout and input language is set to English US...