Linux Mint Forums

Lets say you right click the desktop and select create launcher. Then you get a dialog and in the upper left corner is a button with the text "No icon"
Push it and you see a bunch of icons....
The pdf error seems a bit odd, but it's probably some error in the file association
Right click on a pdf, select "Properties", select "Open with" and finally select "Evince" If Evince is not in the list there's a button "Add" at the bottom which gives you a list of all programs.
If that did not help, post back and we'll try something else

Ok - sorry but I think you understand that it's hard to find out what happened.
However I think it's along the lines of file association and/or dependencies.....
or
Open nautilus edit>preferences>preview
Select show miniatures and maybe you get the preview....
but your problem seems a bit wider