Omar is right, only nowadays, the Hotkey to re-calculate the Normals is SHIFT+N…It used to be CTRL+N, but it has changed…it’s something you use all the time and it just becomes muscle memory and when someone asks, “what keys did you press?”, you don’t know…you’ll have to re-enact the situation and look at what your fingers are doing..
Sorry for rambling, remember it’s SHIFT+N.