So you accidentally changed your output aspect ratio to 4:3 and you are trying to bring it back to 16:9?
'Auto' generally has not problem setting 16:9 for 1920x1080 displays. I've also never had an issue manually setting 16:9 via the in-game menu. That said, you can manually set 16:9 via the ini:
(Show hidden files and folders)
C: \Users\(username)\AppData\Local\Activision\CoDWaW\players\profiles\(profilename)
Edit config.cfg (or config_mp.cfg to change MP)
seta r_aspectRatio "wide 16:9"