My custom header disappeared

I noticed this morning that my custom header and standard nav bar disappeared. I’m using the Adelle theme and Firefox as a browser. It’s the same if I click on a specific post, although I can’t switch between pages because my nav bar is gone.

I didn’t change anything and haven’t uploaded any posts since last Friday. It was fine then. My blog is http://www.oneredeemedmom.com.

Any help is much appreciated!