TurboTax support is open from 5am to 5pm Pacific time, Monday thru Friday
Use this website to contact TurboTax support during business hours - https://support.turbotax.intuit.com/contact/
Support can also be reached by messaging them on these pages https://www.facebook.com/turbotax/ and https://twitter.com/TeamTurboTax
If you bought a CD then you can download the program and use the activation code that came in the box along with the instructions.
How to download 2019
How to install 2019 on Windows
How to install 2019 on Mac
If you used the Desktop CD/Download program for 2019 you will need to have the tax return file ending in .tax2019 from the old computer to open in the program to amend. It would only be saved on that computer and any backups you made. Do you have that file?
If you don't have the file you will first have to recreate your 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.