You should be able to redownload the app from where you bought it. if not contact support. However, if you did not make offline backups of the actual tax file and return, they're permanently lost since Turbotax does not have copies. You can get a copy of your actual return from the IRS for a fee by filing form 4506 or a transcript by filing form 4506-T. a transcript can be obtained online by registering with ID.ME
support:
5am-5pm Pacific Time (8-8 Eastern) Monday - Friday
https://support.turbotax.intuit.com/contact
800-446-8848
IRS
https://www.irs.gov/site-index-search?search=4506&field_pup_historical_1=1&field_pup_historical=1