Windows 10 Start menu and/or Cortana not opening

[Aukerman]

Open Windows PowerShell as Administrator

Method 1:

    Press Windows Key + R on your keyboard
    Key in PowerShell and hit Enter.
    Right click on the PowerShell icon on the taskbar and select Run as Administrator.


Method 2:

    Right click Start button
    Choose Command prompt (Admin)
    Key in Powershell in the black window and hit Enter.

Paste the following command in the Administrator: Windows PowerShell window and press Enter key:

Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}

Wait for PowerShell to execute and complete the command. Ignore the few errors (in red color) that may pop up.
When it finishes, try hitting Start and hopefully it’ll start working. If not, this solution won’t apply to you, unfortunately.