I can't add any layers, or remove, or even look at them. I have the layers tab, but it had a lock symbol. If I go to settings and then dockers, it says "Layers" with a check next to it, but it's sort of gray as if unavailable. If i click on the box with the check, nothing happens.

that's a bug that sometimes happens and we don't know how or why. you can get around it by using the button at the top right that gives you a menu of workspaces to choose from. i generally use "default" or "big paint" 1 or 2.

to clarify, the button is in the toolbar (at the same height as the size/opacity sliders and the "eraser on/off" button, but it's aaaaaaaaaall the way on the right side, with a large gap between the last thing on the left and the button on the right.