Try uninstalling the TurboTax program and then reinstalling the program. You need to follow all the steps outlined in the article below (its a bit tedious to uninstall TurboTax on a MAC, but you have to follow all the steps or you may not fully uninstall the program). After you have reinstalled, you should be able to open the .tax file again.
Please make a copy of your .tax2017 file and put it on a USB or other device before you uninstall. While the file is separate from the program, you don't to accidentally erase it during the process.
https://ttlc.intuit.com/replies/3301991
