Drawings not showing up

[Stuart35415916jpa0]

I am drawing a simple picture but nothing I change in the main window affects it. I mean like I try to erase or draw and it doesn't show up in the main window, but I can tell it's doing something because it changes it in the little layer thumbnails. I have tried reseting preferences and restarting photoshop. Any help would be apreciated

[Semaphoric]

You have 4 layers in a group, but the visibility icon is not set for the whole group. Note that the layers are marked as visible, but greyed out. once you set the group visibility icon, you should be good to go.