User was deleted system and files apparently are gone

We have some important common folders between a number of users. One of the users uploaded very important documents into many folders that we all used. He left the company about a year and a half ago, but his folders and files stayed and we continued to use them. Some time passed, but now we need the folders and files again. I found old emails that we used to share one of those folders and when we click on the link we get an error that the folder could not be found. I don't see the user in other folders that he used to be listed in. This is critical! Can the folders and files be recovered!!??