The 2021 Desktop program is still available until they close 2024 and put 2024 in the past year products around mid October. Then 2021 will drop off. So you better buy and download 2021 right away. 2023 Desktop program is also available. You can't use the Online versions for 2023 or prior.
If your 2021 return rejected you can download the .tax2021 data file from Online and fix or finish it in the Desktop program. Why did it reject? It might not need fixing and you can just download the pdf and mail it without needing the 2021 Desktop program.
How to finish a return you started online
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-finish-a-prior-year-return-that-i-...
If you can't get the side menus to open up to access the prior year..... You need to start entering some basic Personal Info in 2024 for the side menu to open up. Just continue a little ways into 2024.
