If you’re running Windows 10 and have ever run across the error above, stating: “Critical Error Start Menu and Cortana aren’t working”, then some of these solutions might fix the problem.
#1: Try A Full Normal Reboot
Since your start menu isn’t working, you need to hold down the Shift key, while pressing the power option. The restart icon will appear, click on that.
Another way of doing it is by entering the Window Recovery Environment > Troubleshoot > Advanced Options > Startup Setting > Restart.
#2: Try Safe Mode or Safe Boot
Another possible way to fix this issue is to boot the computer into Safe Mode, let Windows fully load, then reboot into normal mode and see if the error goes away. I’ve read multiple reports where this simple task fixes the problem. Unfortunately, this is not a permanent fix and it is not a true solution to the issue, but it seems to work for about 95% of the users that have reported this issue.
Press the Windows key and R key together. The Run command box will open, type msconfig.
In the System Configuration Utility, click on the Boot tab. Click on the Safe Boot checkbox, then select Network. Click Apply and OK to reboot into Safe Mode.
After your system reboots into Safe Mode, go through the steps above, and uncheck the Safe Boot checkbox, then click Apply and OK to reboot into Normal Mode.
#3: Try This PowerShell Script
Step 1: Open the run command by pressing the Windows key and R key together, type PowerShell and press Enter.
Step 2: On the icon of PowerShell, right-click and you will get the option of Running it as administrator. Go for that option.