Applications no longer starting (Resolved thanks!)

I little while ago I installed 12 KDE and did my first update yesterday.
Now many of the applications won’t start. Many of the icons at the bottom of the page are now appear to be gears.
Clicking where the icons use to be I get the following message:
Unable to run the command specified. The file or folder file:///usr/share/applications/calculate-videoplayer.desktop does not exist.
The only change in the message being videoplayer is replaced with terminal/ text editor/ Chronium / writer and the like for 9 of the 13 icons.
Midori which I installed just times out without a message.
Clearly I have missed something, but I have no idea what.
Hopefully it is something minor.
Any help would be appreciated.

I’ve just realised I put this in the wrong place. Sorry.
Can it be moved please… I’m not having a good day.

Same thing happened to me… in KDE too

So how did you fix the problem ?

Run <> in terminal

I should have spotted that myself.
Thanks for your help