In 2014, Turbotax implemented a new password procedure in which your password was linked to your turbotax web site account password. This would in theory allow customer support to unlock your file if you forgot the password. The feature did not work very well and was eventually abandoned.
Make sure you have internet access, and try unlocking the file with your current turbotax online account name and password. If you get it open, save a copy without a password. (There are better ways to encrypt documents on the Mac anyway.)
If you can't get it open, you will need to contact customer support. Customer support hours are given below. To contact support, use this web form and type your question or a keyword. You will get an appropriate phone number for your issue. (You will not get a phone number if you use the link outside of operating hours.)
https://ttlc.intuit.com/replies/3300041