Fix: Start menu, Cortana and other apps not working in Windows 10

After upgrading to Windows 10, some users are reporting that they are unable to open start menu, cortana and other apps in their computer. Most of them got the resolution for their problems by contacting Microsoft Support but due to the long wait time and call disconnection issue, lots of users are trying to search the web for resolution. If you search query made you open this page, then I'm sure you're gonna find the solution for your problem  here. Just read the possible solutions below and you might get your issue fixed in minutes. :-)

Solution 1: Using windows PowerShell
1. Open command prompt with admin rights (press Win+X keys and then press A key) and then type the command sfc /ScanNow and wait for the scan to complete.
2. Now type powershell and press enter in the command prompt window. It will bring Windows PowerShell terminal in command prompt.
3. Now copy and paste the following command and press enter key:

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

4. You will see that the command is being processed (if you see some red colored error messages, ignore them and wait for the command to get executed completely)
5. Once the command execution gets completed, exit from command prompt window and then try opening start menu. It should open now (if now, try to restart computer and then open start menu)
6. If the issue is still not resolved, try to run the following command in Windows PowerShell with admin rights:
Get-appxprovisionedpackage –online | where-object {$_.packagename –like "*windowscommunicationsapps*"} | remove-appxprovisionedpackage –online

Solution 2: End windows explorer task and re-run it
1. Open task manager by pressing ctrl+shift+ESC keys.
2. Click "Details" tab and select "Explorer.exe" process.
3. Now click "End Task" button.
4. From task manager, click "File" and then "Run New Task" option and then type "explorer.exe" and hit enter key.
5. Your start menu should work now.

Solution 3: Create a new local user account
1. Open command prompt with admin rights.
2. Now run the following command to create a test account:
net user /add test 000000
Here, "test" is the username and "000000" is the password.
3. Now run this command also to add the test account in the group of local administrators.
net localgroup administrators test /add
4. Now logout from the current account and login to the test account and check whether issue is resolved.

[If you don't want to use command prompt, you may open run and then type compmgmt.msc and then click OK. This will open computer management. Now click "Local users and groups". Now open "Users". Now you will see the list of available users in the computer. To create a new user, just right click in the empty area under the user names and then click "New User". In the user creation box, just enter the username and password details and click "Create". Your new user account will be created.]

Solution 4: Fix AppLocker in windows 10
1. Press Win+X keys and then press A key to open command prompt with admin rights.
2. Now copy and paste the following command in command prompt and hit enter key.
ren %windir%\System32\AppLocker\Plugin*.* *.bak
3. Restart your computer. Issue should be fixed.

Solution 5: Starting the Application Identity service.
1. Open run by pressing Win+R keys.
2. Now type services.msc and click OK.
3. Search for the service Application Identity and right click on it and click Start.
4. Restart your computer.