Open a terminal, type in
xev
xev is going to record your keystroke and print out the key values in your keyboard page that correspond to your keystroke
example:
KeyPress event, serial 36, synthetic NO, window 0x2a00001,
root 0x2d7, subw 0x0, time 18192998, (183,236), root
270,389),
state 0x11, keycode 11 (keysym 0x40, at), same_screen YES,
XLookupString gives 1 bytes: (40) "@"
XmbLookupString gives 1 bytes: (40) "@"
XFilterEvent returns: False
This will tell us if your keyboards key page is wrong and then we can assume that's the problem or perhaps it's a setting in this infernal gnome malware they slathered all over the thing.... eh, I mean the desktop environment.