If it was rejected for AGI—-be aware that many 2019 returns took so long for the IRS to process that your 2019 AGI might not be in the IRS system.   Try using zero instead.

If filing with zero is rejected then file again but select the option that you did not file last year.  The IRS does not see that question and it will allow you to e-file with no AGI question.

Or—-if you filed as a “non-filer” just to get the stimulus check on a 2019 return, try using $1 as the AGI.

https://ttlc.intuit.com/community/agi/help/where-do-i-correct-my-agi-in-turbotax-online/00/26311

If that does not work and you still cannot e-file, then print, sign, and mail your tax return.

https://www.taxpolicycenter.org/taxvox/are-irs-security-tools-blocking-millions-people-filing-electr...

If you find that you have to mail your tax return then when you choose to file by mail it will print out the pages for mailing and there will be mailing instructions with the addresses you need to use.   The state forms will have the state's name on them.

https://ttlc.intuit.com/community/printing/help/how-do-i-print-and-mail-my-return-in-turbotax-online...

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.

Federal and state returns must be in separate envelopes and they are mailed to different addresses.  Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.