If you did not receive IRS refunds, check the refund status here: https://www.irs.gov/wheres-my-refund.
If you are sure about the missing refund, you need to start a refund trace by calling and speaking to an IRS agent 800-829-1040. You could also fill out IRS form 3911. You could fax the form to the appropriate number here: https://www.irs.gov/forms-pubs/about-form-3911.
You should place an identity protection pin on your file with an agent.
Related IRS Collection Options
The appropriate collection strategy may depend on the taxpayer’s finances, filing compliance, assets, collection deadlines and current IRS enforcement activity.