The following reports are used in the Refund & Lost Inventory Reimbursement Checker (you may have to copy/paste the URLs since Amazon no longer allows direct linking)
Sales Data (for refunds) - https://sellercentral.amazon.com/payments/reports/custom/request
Inventory Adjustments -https://sellercentral.amazon.com/gp/ssof/reports/search.html#orderAscending=&recordType=INVENTORY_ADJUSTMENT
Reimbursements - https://sellercentral.amazon.com/gp/ssof/reports/search.html#orderAscending=&recordType=REIMBURSEMENTS
Returns - https://sellercentral.amazon.com/gp/ssof/reports/search.html#orderAscending=&recordType=CUSTOMER_RETURNS