You have to file a 2021 tax return and complete the Recovery Rebate Credit section on the return.
To complete and file a 2021 tax return using TurboTax you would need to purchase, download and install on a personal computer one of the 2021 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
A 2021 tax return can only be printed and mailed, it cannot be e-filed using TurboTax.
If you have already filed the 2021 tax return then you need to amend the return that was filed.
See this TurboTax support FAQ for amending a prior year tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-a...
You should also check your IRS tax account to make sure that the stimulus payment of $1,400 was not already issued to you by the IRS - https://www.irs.gov/payments/online-account-for-individuals
This answer has been verified for accuracy by an Intuit expert employee
