PDFFORMAT missing

When I go to open up Illustrator (every other program works but this one) It comes up saying that PDFFORMAT.aip is missing. I've checked and its definitely there, but upon trying to trouble shoot this myself I noticed that people were saying my program wasn't in the original file anymore so that could be causing it. But heres the thing... I have the icon and program but no Illustrator file. I have Files for every other Adobe program but Illustrator for some reason. What can I do?