I have suddenly developed a problem with the layers in the drawing I'm working on. Layer 1 (original sketch) is at the bottom of the list'; layer 2 is in the middle and includes all the colouring I have done over the sketch; and layer 3 is all detail work and is at the top.

I just had layers 2 and 3 visible for a short period of time while I was finishing a part of my drawing - now I have made layer 1 visible again it is now only showing that layer and layer 3, despite being 'underneath' layer 2. When I have them all visible I can see some faint colour on top of the sketch in layer 1 (plus layer 3) but that's it. It's driving me crazy because I just spent a day fixing another problem with Krita, and now I can't continue with what I'm doing again!

Any advice on how to fix this problem would be appreciated. I am no techie and only have a basic understanding of this program.

Check that the layer is in full opacity, (at 100%) and that is not on any "blending mode", (in top of the opacity control) should say "normal".