When a Parallels Virtual Machine is left unattended for a long period of time, it is common for it to get stuck on a black screen, where closing the application, restarting, and reopening will not fix the issue. When Parallels opens back up it only gives the option to resume the machine that is "Suspended" but not actually shut down. To fix this issue, do the following:

1. Select "Action" from the Virtual Machine's Toolbar
   
   If the toolbar isn't visible, you need to exit full screen, or move the mouse cursor up towards the top of the screen until it shows up.
   


2. Select "Stop" from the Actions menu
   
   
   


3. Confirm you want to Shut Down and Stop the Virtual Machine
   
   
   

At this point you should be able to start up the Virtual Machine again like normal. It is common however for the Virtual Machine to then have an issue shutting down, where it continuously restarts. If you run into this issue, follow the instructions HERE.