To attempt to remedy the problem, you could run an administrative CMD prompt and issue the command: SFC /scannow. That will scan for and attempt repair of any corrupt files. You could also download MalwareBytes, get it up to date, and scan for malware. If you've enabled System Restore, you could try going back one restore point.
As a circumvention, you could install the free Classic Shell or the $5 program Start10.
I installed the free upgrade for Windows 10 after it became available earlier this year. A couple of weeks ago my "Start" menu button quit working. I can shut down my computer by right clicking and selecting "shut down".
Now I'm ready (or as ready as I will ever be) to tackle the task of getting the issue corrected.
My first thought was to uninstall 10 and go back to 7 (which I was happy with but that's another story). But after some searching I found that it's past the 30 days and it's seems like a lot of work to uninstall now. Frankly, I just don't have the energy to devote hours to figuring out how. I will just live with 10 if I can get the darn Start menu to function again.
How do I get the Start menu working? Any help will be very much appreciated