I'm presumably doing something dumb - can anyone advise?

I installed Windows 10 a few weeks ago (perhaps wish now that I had gone on to a clean install).  From the beginning, two of the taskbar icons weren't working (Search, Edge - with this, if I click on it, there is a brief flash on the screen but the application doesn't load).  I had upgraded from Start8 to S10, and began to wonder whether that might somehow be the problem.  I uninstalled S10 (with Revo), but that didn't cure the icons problem, so I reinstalled.  The problem is that the two icons are still not active, and S10 itself now appears not to be working either though Task Manager says that it's running.  I can right-click on the start button, and that brings up the usual commands, but even here "Search" doesn't work.

Any ideas?  Could there be a clash with another application?  I don't know whether S10 is even imnplicated in the problem.

Any solutions welcome...

Thanks.

Steve