Finder Window when Uploading or Opening Files Missing Items
When finder is the current app, hit  command  and  ,  at the same time. Click the Sidebar tab. You can then select the things you want to show up in window. If they are already selected, try un-selecting them and re-selecting them.

Edit: As @NetherLinks mentioned, a few good answers are over at &quot;File Open&quot; dialog is missing sidebar items. Try them if mine doesn't work.