Alternatively, open up <Your Drive>:\Users\<Your User Name>\Documents\Battlefield 2042\settings\PROFSAVE_profile with notepad or some other text editor, and
Find and Remove these 10-12 lines that have:
Save, and start BF2042. That way you don't lose ALL of your settings. My game seemed to autofill mouse for mouselook, so I didn't even have to reassign keys after that, it just worked finally in game.