Have lost access to Action Center and Win10 Start Screen

Hi,
Yesterday I lost access to the Action Center and the Win10 Start Screen on a new laptop (Asus) with Win10 Home. I was creating a Rescue Disk when my cat walked across my keys and everything blinked black. Sigh. I have since recreated the Rescue Disk. I am batting zero on solutions to the current missing items.

The Windows key + "a" shows me the Action Center panel and so I know it is there. I do not know the key combination to bring up the Start menu. (Even the answer here would help.) TIA

Thanks, but that I know very well. It is the malfunctions that annoy me. However, guess what?! The cat walked on the keys again; she never did this with the old laptop . . . . I checked and both the Win10 Start Screen and the Action Center are back and responding normally on the laptop.

Now I shall just cross my fingers and hope to stay out of that tangle, which, from reading, may or may not be possible.
Thanks for the quick response!