Sidebar missing in a POST

Hello, I can see my sidebar only in pages but not in posts. I found this thread but the solution didn't work for me because I didn't find "Optional Post Sidebar" in “Appearance => Widget”. HOWEVER It is not just the sidebar that is missing in posts. It is also FOOTER and BACK-TO-TOP-BUTTON. It is quite strange really. I'll be grateful for any help. This is the site: http://eshop.byethost33.com/ And HERE is a POST (with missing elements): http://eshop.byethost33.com/ale-no-nehovor/