This error may occur if some files or system folders have corrupted due to a malware attack, or you might have made changes during installation or uninstallation due to which its happens. This error could be for your start menu, or start menu and cortana. Before following further steps create a restore point so that if something goes wrong then you could revert back.
1. Run cmd (admin) using win key + X key and type the following command sfc/scannow. Restart your PC and check if your problem is fixed.
2. Open cmd(admin) and type this Dism /Online /Cleanup-Image /RestoreHealth and then restart your PC.
3. Try disabling third party antivirus and now use the start menu.
4. Using task manager kill the cortana process and restart it. Hope any of them helped.