How can you help me verify my identity for my stimulus check?
No one other than you can get the information required to verify your identity with the IRS.
IRS website for identity verification - https://www.irs.gov/identity-theft-fraud-scams/identity-verification-for-irs-letter-recipients
https://www.irs.gov/credits-deductions/2021-child-tax-credit-and-advance-child-tax-credit-payments-topic-k-verifying-your-identity-to-manage-your-payments