There are other options you can use to obtain your AGI including the account number from your mortgage, home equity loan, home equity line of credit, or your car loan.
Please see the attached link from the IRS for instructions on how to obtain your AGI from them.
IRS transcript request
If you used TurboTax in the past, you can simply log into your account and follow the instructions in the following link.
Accessing prior year returns in TurboTax