Desktop icons somehow not associated with its application - if there a fix for i

[karatearmadillo]

I accidentally did "open with" and it changed a lot of the icons on my desktop. I cannot open any of the files that changed now

 

[The Stealthinator]

Elaborate!

 

[jarotech]

Do the same thing, "open with" and Choose default program...
From there pick the one of the Recommended Programs.