I can't edit a path

[Ofnuts]

To edit the path you  have to:

• Make it visible (eye icon the path list)
  
• Start the Path tool
  
• Get close to/over t it with the mouse cursor (that should show a hand)    
  
• Click, which should select the path (make the anchors appear)
  

Since you appear to have loaded the path from a SVG file, one possibility is that you didn't check Import paths when opening the SVG so you are only seeing a rendering of the path on a layer and there is no path in the image (in which case if the Path tool is in Edit or Move modes, it will indeed display a forbidden indicator since there is nothing to act on).

Otherwise please attach a screenshot, showing the Path tool options and the Paths list.