For mapping questions, you should either ask it in the
Hammer or
Source Engine discord or either in
r/hammer. Though you need to press CTRL+A to resize all of the windows, or maybe you pressed SHIFT+Z and focused on one window, move your mouse over to the 2d view and press it again. If it still doesn't work, press the button on the top bar that says "load default window state". Also, please rearrange your window layout, this hurts to see : close the manifest window and move the entity / prefab selector to the other column. You should also use H++ and join the
Portal Series Beta Research if you want feedback about your mod.
https://developer.valvesoftware.com/wiki/Hammer_Hotkey_ReferencePS: you shouldn't have a file structure this complicated, put your maps either in a mapsrc/ folder in your mod directory or put in an easy to access to folder