If you were a dependent in 2020 and 2021 you would not be eligible for a stimulus payment.
If you were NOT a dependent -
Check your tax account to see if the IRS sent the economic impact payments. EIP1 was for $1,200, EIP 2 was for $600 - https://www.irs.gov/payments/your-online-account
If you were eligible for the payment and the payment is not in your account then you have to file a 2020 tax return for the Recovery Rebate Credit. Or if a 2020 return has already been filed you will need to file an amended 2020 tax return.
EIP3 was for $1,400. Check your tax account.
If you were eligible for the payment and payment is not in your account then you will have to file a 2021 tax for the Recovery Rebate Credit. Or if a 2021 return has already been filed you will need to file an amended 2021 tax return.
If your tax account shows that the economic impact payments were sent by the IRS then will have to initiate a trace on those payments.
Go to this IRS website for initiating a trace for EIP1 and EIP2 (QF8) - https://www.irs.gov/newsroom/2020-recovery-rebate-credit-topic-f-finding-the-first-and-second-economic-impact-payment-amounts-to-calculate-the-2020-recovery-rebate-credit
Go to this IRS website for initiating a trace for EIP3 - https://www.irs.gov/newsroom/questions-and-answers-about-the-third-round-economic-impact-payment-topic-j-payment-issued-but-lost-stolen-destroyed-or-not-received