How to fix toolbox prompt "not available for write access"? (frustrated!)

Just this morning it was fine and now toolbox says that I can only create derived parts. I found several ideas having googled this error one of which is to check default files location and properties in windows explorer. However, I just can't move on if the solution not laid out step-by-step.

I've been stuck with this problem for hours, frustrated and currently re-installing the software. Help!

SolidworksToolbox