Keyboard mapping off

This happens a lot actually. Normally it means you have the wrong Input Source active. Go to system preferences > keyboard > input sources and make sure there is ONLY ONE ITEM on the list, and that the name of that item reflects the language of your keyboard, such as US for American, British (and NOT British PC) for British, etc.

If you still have problems, provide details about specific keys not mapping correctly and we can probably give you the fix.

(Having more than one item on the list makes it easy to accidentally change to the wrong one)

Fur-mama wrote:

I won't add it back until I need it

You can make everything you need for French with the US input source, via two different ways -- the accent menu and option key shortcuts.

Enter characters with accent marks on Mac - Apple Support