Well, this usually always solve my buggy Android Studio -

1. Restart Android Studio.

2. Try Again. If it still fails, go to Build -> Clean Project. Try Again.

3. If it still doesn't work, go to File -> Invalidate Cache and restart. Try Again.

4. If it still fails, close Android Studio. Go to your sdk location -> find a folder called "build-tools". Delete that folder. For a safe side, don't delete it permanently. Try Again.

5. Help yourself. Even God can't help you on this now.