How can I find out my Adjusted Gross Income from the year prior when I can't locate my tax return or contact the IRS?

See the sticky at the top of the forum:

https://www.askmehelpdesk.com/taxes/how-get-copy-old-tax-return-irs-318020.html

If you can't contact the IRS and don't have your own copy they you're out of luck, unless you paid a professional to prepare your taxes last year, in which case he/she should have kept a copy.