Individual posts do not show sidebar on the right

Hi all! Sorry, basic question here: If I enter the main page of my blog (https://www.lonifasiko.com), I see posts excerpts and the sidebar on the right, with some basic widgets.

But when I enter a concrete post and unique URL (e.g. https://www.lonifasiko.com/2013/06/13/castillo-de-davalillo-guardian-de-la-sonsierra-la-rioja-alta-rio-ebro-briones-san-asensio-siglo-xiii-ataques-navarros), only see the content of the post and the header are displayed, but I cannot see all the widgets in the right sidebar, and I think I’m missing the opportunity of readers reading more content in the blog. How can I make all individual posts show also the sidebar? Must be silly but I don’t know how to fix this.

Thanks very much in advance!

Regards,
Miguel.