title: Android view in Android studio says "nothing to show", can't run app anymore either
body: <p>I tried some things with vcs, git, not sure what I did. Suddenly my Android view says nothing to show:
  <a href="https://i.stack.imgur.com/LhZW0.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LhZW0.png" alt="Android View"></a> </p>
  
  <p>However here's my Project view showing everything correctly:</p>
  
  <p><a href="https://i.stack.imgur.com/U55Yu.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/U55Yu.png" alt="Project View"></a></p>
  
  <p>I also can't run my app anymore, it prompts me with run configurations. 
  <a href="https://i.stack.imgur.com/JjhRC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JjhRC.png" alt="Run configurations dialog"></a></p>
  
  <p>No idea what I did wrong.</p>
  
  <p>Edit: I fixed it, luckily I backed up the project beforehand, simply replaced the whole folder of the project with the backed up folder.</p>