All pics have disappeared except last 6 months.

I have Adobe Photoshop Elements 6.0. All of my previous years of pics have disappeared except the last 6 months. On the right-hand side, it says "show the last 6 months."  When I click on "show all" nothing more shows up but the last 6 months of pics. I have tried to drag the timeline to an earlier date, but that doesn't show any pics either. Please help!