cant login. changed keyboard setting fron English to French

You can change the keyboard's language setting from one language to another by pressing Command-Spacebar although this may not work until after you've logged in.

Different language settings for the keyboard can move characters to different keys than those you're used to. Here are the layouts for U.S. English and European French -

English -

French-

iOS doesn't run on IMacs. Nor does Classic refer to any operating system that can sync with iOS 10.

Look for the keyboard icon on the menubar. That usually lets you switch keyboard.