I think somehow all your fences have move to you other Desktop pages. In your case its on the left desktop pages. That why you need to press Alt+left to move to that desktop pages.
What you can do is, Log in, Press Alt-left to go to that Left desktop. click & drag all your fences, one at a time, to the right just until it move to the center desktop and release the mouse. That should do it. Then go to layout & snapping on your fences setting. Layout snapshots and take snapshot to save that setting. Just in case it moved again. You have the snapshot to restore back to.
Try that and let us know.