I have Windows 10 Pro Technical Review installed on a virtual machine at work and all was going swimmingly until the updates came along a while back and pushed it to Build 9926.
That was the end of the Start menu, it just vanished. I made a bunch settings and config changes as advised by various forum posts, including some from Microsoft employees, and rebooted countless times but no dice. Clicking on the Start menu was as useless as doing so on Windows 8.
Eventually I decided to run Windows Update manually (wuapp.exe) to see if any new updates would fix the issue, but every time I ran the command I was greeted with the dreaded error message: This app can't be activated by the built-in administrator. Yes, I log in as the Administrator on that machine, and why the almighty account can't run an application is beyond me.
Thankfully this article saved the day. After enabling the policy, User Account Control: Admin Approval Mode for the Built-in Administrator Account and a reboot, I was able to run Windows Update.
But as a side effect, the Start menu suddenly began working. Had this policy change fixed the problem or was it just a coincidence? Maybe if you have the same issue, you can try the same action and report back if it fixes the problem. Right now I'm too elated to have the Start menu back to undo the change and test the theory.