Simple Dark Theme Widgets won't display

I have not been using the sidebar on my site valkilmer.com except for search. Now he wants a photo gallery widget. I installed NexGen and got it working fine, but when I went to add the widget it wouldn’t display. Then I tried adding other widgets (which I had used in the past), and they won’t display either. I welcome any thoughts on the origin of this issue as I’m at a loss. Thank you in advance!