Hello Wrecks, and welcome to Seven Forums.
First, double check to make sure that your Windows 7 has been or still is activated
. If not, it would turn your desktop to be solid black like this after 30 days of being installed until it is activated.
Next, see if you may have checked the Remove background images (where available)
box in Ease of Access Center.
Another item to check is if you may have used the tutorial below to specify a desktop background and prevented it from being changed.
Desktop Background - Specify and Prevent Change
Hope this helps,