If you do need to file an amended 2020 tax return:
I'm not sure what you mean by "cd wasn't working so had to file manually." When you say "cd wasn't working" do you mean that you were not able to use TurboTax at all? When you say "had to file manually" do you mean that you filled out paper forms by hand in order to file the tax return?
If you did not file the original tax return with TurboTax, amending it with TurboTax will not be easy because you don't have the original tax return in TurboTax. An amended return uses the original return as a starting point. If you don't have a .tax2020 file for the original return, you would first have to recreate the original return in TurboTax, making sure that it exactly matches the return that you filed. Then you would use that recreated return as the starting point for an amended return.
If you purchased a CD from Costco, I don't think your license code would be on the TurboTax web site. You probably have to contact Costco for help. You could try calling TurboTax support and see if they can help you.
