With my business laptop running Windows 10 enterprise, I experienced a problem with a START Menu not working, Cortana not working. After googling I found this method which works fine in my case:

Before you proceed, you may want to create a system restore point first, so that you can revert back, if you find that the results are not what you expected.

1) Run the following command in an elevated command prompt, to run the System File Checker.

sfc /scannow

Restart after the scan is over and see if it helped.

2) Repair Windows Image. Open an elevated CMD copy-paste the following and hit Enter

Dism /Online /Cleanup-Image /RestoreHealth

Restart after the scan is over and see if it helped.

3) Make Start full screen and back. Enable Tablet Mode and Start Screen and then go back. See if this toggling has helped.

4) Use the Windows 10 Start Menu Troubleshooter from Microsoft.

5) Open an elevated PowerShell window.

NOTE: After the November Update, if you use this method  to fix this problem using the Appx PowerShell cmdlet, it may break your Windows Store apps. But if you have installed Windows 10 Anniversary Update, it is working now.

To open an elevated PowerShell prompt, type PowerShell in taskbar Search, and in the result ‘Windows Powershell’ which appears, right-click and select Run as administrator.

Type the following and press Enter:

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

Also rename the c:\users\<>\AppData\Local\TileDataLayer dirctory to  go to c:\users\<>\AppData\Local\TileDataLayer_old

NOTE: after correction remove the _old directory

6) If Cortana or Taskbar search is not working, open Task Manager > File menu > Run new task. Type powershell and select the Create this task with administrative privileges check box and click OK. See this post if your Taskbar is not working in Windows 10.