Phantom storage

So a couple of months ago, I booted up my Mac for work, and logged in to my work account. After starting up, everything went back to factory settings (display was Mavericks background, settings went to regular apple). I looked around and everything was gone. It was basically like it started a brand new guest account by itself. Some of my work was gone, but since everything was saved to Dropbox, I just created a new account and put everything on there. Now everything was back to normal after setting the new user account how I like it with all my apps and programs reinstalled.

Well, after doing some maintenance, the storage is wacky. I have DaisyDisk to have an overview of all storage I'm using, and it says I have 48 GB left out of 1 TB. So apparently I've used 999.2 GB of disk space. BUT DaisyDisk and Finder only shows that I've used 500 GB of disk space, so I cannot delete anything that it cannot see.

I have a feeling that there is another 500 GB of space still in the computer somewhere from that other account that went mysteriously missing before. So how can I access this user account? I've deleted it (or so I thought).

Or maybe this isn't the issue. I don't know. I need help.

Basically, I have 500 GB or storage that I cannot access to delete. It says it is there, but not there.