Desktop icons have disappeared after using HDMI cable (Yosemite)
I had the same problem, I think. But my files were still in the finder under 'Desktop', just not on the actual desktop. After trying a few of the above, I second-clicked the desktop and hit 'Clean up', and they all reappeared. So the simplest of all helped for me.
This just happened to a teacher at my site. After repairing disk permissions (Disk Utility) and restarting the computer, everything reappeared.
Try rightclicking the mouse on the desktop, and choose "Clean Up" - it worked for me :)