Unable to open old projects in unity 5.3.1?

I need to open old projects for a class assignment, but when I try to “open” and browse for them it doesn’t recognize any of the project folders as Unity projects? I’m not sure what version I had before, but it is not on my computer any more…not sure what happened, so I don’t know how to check the version they are from either.

Check out this link and see if it will help you:

To check you version of Unity for a project, first, are you on Mac or Windows?