So restart the PC to see if anything changes. If Ctrl Alt Del doesn't work then press and hold Power button, then power back on to see what happens and report back.
Are you running the Upgrade to Version 1903 by installing Media Creation Tool, opening the tool and choosing Upgrade this PC now?
If so and it won't progress move to the next step to use the media to Upgrade version following these steps for Overcoming Version Upgrade hurdles: http://answers.microsoft.com/en-us/windows/wiki...