Failed Boot After Windows Update

When I switched on my PC this evening a large message appeared to say that updates were being installed & that this might take a few minutes. 45 minutes later I had a grey screen with nothing on it. I left this for about an hour whilst I went out, still the same when I came back so I did a hard re-boot. Now, the PC starts, I get the log on screen & log on then just get a grey screen. Occasionally some of the tray icons appear but cannot be clicked. During start up a message flashes up too quickly to read but it's about system32....something....desktop file not accessible. Any suggestions?

Win10

 

Update, had to have an 'over the top' re-install of Windows. I had to get a local computer shop do this as, having upgraded from Win8 to Win10 I do not have an install disc. All seems to be working OK now & no loss of data.

 

No need to pay - you can d/load Win 10 from MS if you have access to another computer.