Same thing happened to me. I was unable to access the 2019 and 2020 software that I have on my laptop. It was asking for the activation key, which I no longer have. I called Turbo Tax and was given some fixes in the link below, but none of them worked. I was told that TT is working on correcting the problem and once it is corrected, I should be able to access the 2019 and 2020 software. Here is what they sent me:
Attached is a link to TurboTax Help site article concerning your current login issues on TurboTax Desktop for 2019 and 2020.
https://ttlc.intuit.com/community/tax-topics/help/turbotax-2019-requests-license-activation-at-every...
I am certain this issue will be resolved soon. Since you currently do not need to access or amend the prior year returns you can allow our tech services to correct the issue for your future use.
