I filed 2018 taxes with Past Year Tax Website last month but i dont have a copy of the Adjusted gross income so how can i E file 2019 with Turbo Tax now?

use 0 since the return was filed so late. 

If you only filed 2018 a month or so ago, the IRS does not have your 2018 AGI in the system so they cannot match it when you try to e-file 2019  Try using zero.  If zero does not work then you have to print, sign and mail 2019.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.