Pages dissapearing?

So I already had a few pages made and displayed on my sidebar. Since then I have been struggling with a few different flickr plugins (to try and make a gallery show up on one of my pages, still haven’t figured it out)…anyways. Now I click on the pages and it says they don’t exist? I went to my manage>pages and they are still there with the content in them but don’t show up when i click them from the main page. What did i do?