Hi
I don't think so. 
If you just clicked "Save Project" it overwrites with the same name effectively cancelling the old one. You may be able to recover deleted files (or some of them) with one of the specialized programs for that purpose as the "New" project probably won't occupy the same disc areas as the old one which will have been simply marked for overwrite, but even if it works, it's doubtful if you would pick it all up.
However if you actually started a NEW project,as you say, then you would have been prompted for a name at the "Save" step irrespective of which one you picked. If you have entered (or chose) the name of an already existing project and saved it to the same location you would have got a warning that there was already a project with that name and did you want to continue. Clicking "No" would have brought you back out. Clicking "Yes" would have overwritten it. You would have had plenty of warning. 
I am afraid the lesson here is always to use "Save project as" if you think you may need to go back to a previous editing stage, and always to start a new project when it is a new project (not simply delete the files of an existing project as this does not cancel the name)
Sorry.....
Nat