Re: Layer issue: Layer isn't working correctly anymore. First I put in background, then a few other layers. Each time I add a layer, I canNOT go back to work on a previous layer. How do I return things to normal? Thank you!

A screen shot of what you see may help us diagnose what's going on.

Other than that, when new strange behavior comes around, the thing to do is reset the preferences: Preference file locations | Photoshop Elements and Premiere Elements

Also, uninstalling and reinstalling will not cause you to loose anything, all of the images and such will still be around afterward.