1400 was the 3rd Stimulus payment. It came out starting in March 2021. If you didn't get it you claim it on your 2021 return line 30 as the Recovery Rebate Credit. But Line 30 is only if you didn't get the full amount or qualify for more. If you didn't get it you have to file a 2021 tax return or amend 2021 if you filed without it on line 30.
Double check your bank statements and Check your IRS account to see when and what they sent you (check both spouse's accounts if married)
Your Online Account | Internal Revenue Service
If the IRS thinks they sent it to you but you didn't get it request a trace for a missing third Stimulus payment
https://www.irs.gov/newsroom/questions-and-answers-about-the-third-economic-impact-payment-topic-j-payment-issued-but-lost-stolen-destroyed-or-not-receivedYour Online Account | Internal Revenue Service