Why is the Start Menu not opening? (Windows 10)

[Windows Central Question]

So I log in, I do stuff and the start menu works. But after a while, the start menu will not pop up. The taskbar is there, and I can see the start menu, but if I click on Cortana or the start menu nothing will pop up. The start button on my keyboard is also not working when this happens. Is there any fix because I've searched on forums and found nothing :/