My blur tool does not work half of the time when I'm trying to blend background from subject after using the lasso tool to change subject brightness, etc. I try to use the blur tool to fade away sharp edges and it won't work. I create a new layer, then try and nothing. Please help!!
Try converting the background layer to a normal pixel layer. The blur tool should be able to blur the background layer It will not work on a smart object layer, shape layer, text layer etc. Are you sure you deselect ed you may have a hidden your selection ctrl+H you could also try fading/feathering your selection before making your brightness change. If you added an adjustment brightness layer the blur tool will not work on the layer just the layer mask can be blurred so you should be able to feather your lasso selection in the layer mask.