How to get my photos to save to my computer?

Hello, I am having this problem where I cannot seem to get my photos to export once I have edited.. 

I have tried setting up a new folder (and even an older one) and it does not work.  It tells me that I "do not have access to save photos", it happened out of the blue one day. Its only on my lap top not my imac.  

PLEASE HELP, 

i am a photographer and would love to edit on my lap top as well.