All my tracks are locked, what did I do?

I’m using Cubase 8 and I went back to a project to do some editing and the editor wouldn’t open. I discovered that all the tracks are locked. The lock button on all the tracks is grayed out and unlock on the edit menu is also grayed out. I checked earlier versions of the project and the same thing happens. I checked all my current song projects and they are all ok, just this one has the problem. I guess I must have hit some hidden button somewhere, how do I get out of this? Anyone know?

I figured it out myself. All the tracks were frozen, I don’t know how that happened but I just unfroze them one at a time and now they are back.