Just to clarify, are you trying to amend your return but you are not able to, or have you amended your return and cannot open the file on your computer?
How do I amend my 2019 TurboTax Online return?
I am unable to open my 2019 return so I can amend it.
Can you please provide us with more details, what is occurring whe you attempt to open it, are you receiving an error message, etc?