https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/00/27010/message-id/746
You can get a free transcript from the IRS:
https://www.irs.gov/individuals/get-transcript
If you cannot get the AGI then your ONLY option is to print, ink sign and mail in the return. In the future, save a PDF to your computer and/or print a paper copy for your records ... you will need the prior year AGI every year going forward.