What year do you need to amend? The 1040EZ was discontinued several years ago. Everyone files a full 1040 now.
If you didn't use Turbo Tax.
Ideally you should go back to who did it and they should amend it for free if it was their error. To amend a return you did somewhere else or you don't have the original.tax file, you would first have to fill out Turbo Tax like you are doing the original return and pay for it. You have to recreate the actual wrong original return. Then when it matches each line that you really filed you have to tell Turbo Tax you will mail it so it thinks it was filed. Then you can amend it.
For the current year you can use the online version by first recreating the original return exactly as filed. Then pay the fees and say to mail it and print it out so it think you filed it. Then when it matches every line you can amend. How to amend an Online return
Or you can buy the Desktop CD/Download program here, https://turbotax.intuit.com/personal-taxes/cd-download/