You need your 2018 AGI to efile 2019. The AGI is on 2018 1040 line 7.https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/01/25947
You need to register a 2019 online account to access prior years https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/01/270...
When did you file 2018? If it was late in the year or your efile rejects try putting in zero for the AGI https://ttlc.intuit.com/community/rejections/help/what-if-i-entered-the-correct-agi-and-i-m-still-ge...
