To access your prior-year returns that were filed using TurboTax Online, you need to first make certain you're in the same account you used to file those returns. Then you can follow the instructions listed in the FAQ below: https://ttlc.intuit.com/replies/5574744
You can also use the resource below to check if you have multiple accounts with TurboTax. https://ttlc.intuit.com/replies/3302270