You would need the files ending in .tax 2015, .tax2016, .tax2017 and each years program installed to open them. If you bought the program downloads you can download them again. Or install from the CDs.
Or you should have also saved each year as a pdf file when you were done. Look on your backups for all files ending in .tax or pdf. They should have been in your Documents in a Turbo Tax folder.
