Sorry I cannot be more help ... save the PDF and the .taxfile of the original return to a removable storage medium for safe keeping and try the delete and reinstall option mentioned before. Start a fake return so you can install the state program if needed and make sure to run a program update at least twice (for a mac restart the program at least twice). Then try opening the return to amend using the amendment option.
Select your tax year for amending instructions:
For additional information please refer to How to Amend
