Mantra

After I added a background image, I lost my sidebars, which I use for paid ads. Also, after setting the theme, my old posts are not showing, they give a 404 error. They are in my WP, just not showing to the public. I activated them into the menu, which should work in a widget at least, but still not working. this is my web address https://www.latinzonemagazine.com
Can someone help me?