Start by doing a hard reset most of the time this resolves the issue. Unplug it from the charger then press and hold the power button for 20 seconds then boot it back up and see if it will load you desktop screen. If these doesn't work try some of these troubleshooting steps that may help.
- While the laptop is on with only the mouse cursor connect and external monitor and see if you'll get any display from it. If it shows the same black screen with only the mouse cursor you can disconnect the external monitor.
- Press CTRL+ATL+DEL at the same time and select Task Manager.
- Once open click File then select New Task. Type "explorer.exe" and click OK, see if you'll get your normal desktop screen back.
- If these doesn't work I would suggest to just do a factory reset with it since it may be an OS issue.