If you are able to view that Page in your list of Pages, then that means it probably/possibly uses the default Page template (which comes in every theme no matter how custom) which was edited by the person who was originally helping you.
If you create a new dummy/test page, what happens? Do you get the same layout?
You said your Page choices offered Parent and Order which means that there is only one Page template in your theme which makes me think that whoever customized your theme simply customized the default Page template.
In which case, creating a new Page ought to use that same template.
If not, then you will need to create a new custom Page (with the sidebar for the widget) and then style it accordingly to match the Page you want it to match.
Here is some information on creating custom Pages: HERE.