Hi Raymond,

If Start menu reviver and Cortana are not working in your machine, I would suggest you to try the below fixes in order to resolve the problem.

Fix 1: Tweak settings

1. Open Windows PowerShell as Administrator
   1. Right click Start button
   2. Choose Command prompt (Admin)
   3. Key in Powershell in the black window and hit Enter
2. 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"}

3. Wait for PowerShell to execute and complete the command. Ignore the few errors (in red color) that may pop up.
4. When it finishes, try hitting Start and hopefully it’ll start working.

Fix 2: Try the below steps and check after every step.
1. Sign out and Sign in
Sign out and Sign in or restart your PC and see if the problem goes away.
2. Automatic Repairs
If your PC prompts for Automatic Repair, continue with it and let Windows carry it out.
3. Kill and restart the Cortana process
If you find that Cortana is not working properly, the best thing to do would be to kill Cortana process and restart the process via Task Manager. If it was a minor runtime error Cortana would just take a restart to fix it.
4. Disable Antivirus software
Some security software are known to create this issue – Avast for instance. Disable it and see if it makes the problem go away. If your security software is the culprit, make sure you are using its latest version, else you may want to change it.

Fix 3: Create a new User Account
The problem might be associated with your Microsoft credentials. Try creating a new username and password and see if you can fix the Cortana.

Just follow the below steps to do so:

1. Press Windows logo key Windows logo key + R, type ms-settings:, and then select OK. This opens Settings.
2. Select Accounts > Sign in with a local account instead.
3. Type your Microsoft account password and select Next.
4. Choose a new account name, password, and password hint, and then select Finish and sign out. 

Also remember that Cortana will not be switched on automatically and needs to be enabled on by selecting Cortana button on the taskbar.
You can do this by following the below steps:

• To begin with, click inside the taskbar search box. 
• The Cortana settings box will appear as shown below. Move the slider to On position, to enable Cortana, so that it can give you suggestions, ideas, reminders, alerts etc on your device. 
• Also move the slider to the On position for Hey Cortana here. If you scroll down, you will find settings that let you turn on or off, Flights information and Taskbar tidbits.

I hope this helps in fixing the issue.

Regards,
Lokesh