media bay is empty

I am a beginner using elements 7 and am trying to load drums into groove agent but when I open media bay it is empty. I select Drum&Perc and no matter what I select in the the other boxes nothing shows up in the pane below. It is completely empty. Can anyone help

I had a similar problem. I ad to redefine locations and rescan. Then all worked fine again.

how do I redefine location?