Hi, I have problem with no visible site structure panel in editor. I tried drag and drop method, but nothing happens. I use chrome on mac, but I tried these method also on windows but without any result. I do not see any little arrow button in left down corner of editor. 
Please, can you help me with this? I need to find backend file in this structure sidebar. Many thanks!
Have a read of these links here.
https://support.wix.com/en/article/corvid-working-with-the-site-structure-sidebar
https://www.wix.com/corvid/forum/community-discussion/site-structure-panel-isn-t-visible
Otherwise as this forum is for code related issues and yours is editor issues, then you are better suited going through Wix Support for more help. https://support.wix.com/en/article/contacting-wix-support
Also, simply try logging out of Wix, closing your browser and clearing cookies/cache and restarting again your browser and then relog back into Wix.