I had used the prefab FPS Controller. ASD work but the W button don’t want to work. If i try to use the arrow they work. 
Anyone could help me
I assume you haven’t modified the FPSWalker script? Check the Input manager (menu: Edit > Project Settings > Input). Make sure that for the Vertical axis, the “Alt Positive Button” parameter has “w” as the key.
Yes everything as you said but it don’t work.