@yatish sharma I did read mk2022mk answer and if you already tried the 0, then the IRS is not accepting the amount.  TurboTax will not accept the 0.00.  If you cannot get your AGI, you will have to mail in your return.  I have been doing this for over 22 years and never has that worked.  

You might want to read the following:

How do I find last year's AGI?

https://ttlc.intuit.com/turbotax-support/en-us/help-article/internal-revenue-service/find-last-year-...