None of my Pages, Keynote, or Numbers pages will open.

I have the latest versions of Pages (5.2.2), Keynote (6.2.2), and Numbers (3.2.2). I cannot open any of my documents. I get the message:

The file "whatever.document.pages" couldn't be opened.

If I try to create a document, say, in Pages. It lets me created it, but when I go to exit, it prompts me to save the document (which is weird), and when I name the document and hit save, it says

The file "untitled.pages" couldn't be opened.

Very frustrating. I have these apps installed on my iPad Air, and they work fine between my iPad and iPhone (4s), it's just on my iMac that I can no longer use any of these apps!