SOLVED: I had this issue with just the Language Bar showing after the Preview Upgrade. I couldn't access the Start Menu, Settings etc and here is how I fixed it. PLEASE READ EVERYTHING FIRST. Press alt+ctrl+delete - Task Manager - File - Run New Task - msconfig - Click "Services" Tab - Check Hide All Microsoft Services - then Disable All - Click Apply and Restart Later - Also try disabling all Startup Programs - Press alt+ctrl+delete - Task Manager - Startup Tab - Disable all Startup Items one by one. Restart your PC. Don't Worry this may not completely work until the Next Step. If it doesn't allow you to log in the next thing I did was - Press alt+ctrl+delete - Task Manager. Then Scroll all the way down to "Windows Logon Application" then right Click and end process. Your Desktop should be visible now (and should stay that way when you restart) if not try Press alt+ctrl+delete - Task Manager. Then Scroll all the way down to "Windows Start-up Application" then right Click and end process - Your Desktop should be visible now (and should stay that way when you restart) Hope this helped. The first step of disabling all non Microsoft Services and Startup Programs may not be the Issue so this step may not be necessary. Also to be honest I cannot remember if it was the End Process of the "Windows Logon Application" or the "Windows Start-up Application" that did it as I had a few drinks by this stage. Although when you end the Process it takes you straight to the Desktop with everything available. Good Luck, Stay Positive and Be Well.
Thank you SO much. Stopping the startup items and ending the "Windows Logon Application" is what fixed it for me. I didn't have to disable all of my services.