I visited your site and viewed the web page source.
There is an extra full-width class in the div #primary (the blog posts) causing it to expand and push down the sidebar, which is div #secondary. If I remove that, your sidebar goes back in place.
Please see screenshot. http://prntscr.com/7dg3li
I am unable to replicate this issue on my computer. May I know if you have made any modifications to the theme code?
Did you install any new plugins recently?
I will need access to your site to find out what is causing this issue.
Please kindly provide the following details via private reply.
WordPress Login Url:
Ftp Server Url:
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