If you use Google Authenticator or a similar app to generate 2-factor authentication (2FA) codes and no longer have access to your device, you can restore this ability to another device if you saved the secret seed provided when setting up your 2FA device. You may have written down this secret or saved it to a USB drive.
If you've lost your authentication device and do not have access to the secret seed, please refer to this page
for recovery steps.
Originally, to start generating codes you would have scanned a QR code with your phone. The following steps will show you how to generate these codes from only the secret seed for several apps:
When you open the app, add a new seed by pressing the red plus in the bottom right corner. Select “Enter a provided key” from the menu that appears.
In the form that is shown to you, fill out the account name with something that describes this account (such as "Coinbase") and type the seed into the field for the key.
Click the "add key" button in the top right corner of the screen. In the next screen (QR code scanner) click the “no barcode” button. From there you can select “Coinbase,” enter your Coinbase account email and the Coinbase secret seed in the "Account" and "Key" fields respectively.