You are going to have to try to locate the file that Turbotax created when you did your taxes in 2015. I'm confused that you said you downloaded and installed the standalone Turbotax 2015. Why wasn't it on your computer already ? Does this mean you originally filed online at Turbotax's site ? If so, I think you're probably out of luck, unless Intuit can somehow send you a file of your online work (which I seriously doubt). Or did you just delete Turbotax after you were done ? If so, maybe you somehow deleted your tax file too. If you really can't locate it (try OSX's "find" utility ?), then again you're out of luck. At least hopefully you still have a paper copy, so you can type in stuff from it. Good luck.