If he used TurboTax online to file a 2017 tax return then you have to sign onto the online account using the exact same User ID that was used to create the account - https://myturbotax.intuit.com/
If he used the TurboTax desktop CD/Download editions for 2017 then any copy of the 2017 tax return will be on the computer where it was created. TurboTax does not store online any returns completed using the desktop editions.
If you believe he used the TurboTax online editions and you do not have the User ID then you will need to contact TurboTax support and prove your identity to access the online account, provided the return was filed with the filing status of Married Filing Jointly.
Use this website to contact TurboTax support during business hours - https://support.turbotax.intuit.com/contact/
Support can also be reached by messaging them on these pages https://www.facebook.com/turbotax/ and https://twitter.com/TeamTurboTax
You can also get free transcripts of your federal return from the IRS - http://www.irs.gov/Individuals/Get-Transcript
For a fee of $50 you can get a complete federal tax return from the IRS by completing Form 4506 - http://www.irs.gov/pub/irs-pdf/f4506.pdf
