Jpegs won't upload after version 4.1

When I try to upload jpegs in to the media file, I get the following message:

Error “sample”- Gold Creek L…ding 100.jpg
Unable to create directory wp-content/uploads/2015/01. Is its parent directory writable by the server?

A pro built my site but I can’t reach him. I needed to make my media file jpegs smaller and get rid of the big files which seemed to jam up the process and keep my images square. It loaded before; now it doesn’t. I’m a newb so please be gentle with me!