How do I cash a life insurance check if the check is made out to myself as admistrator and also says to the estate of the deseased person?

Take your court-issued Letters Testamentary or Letters of Administration and an EIN (available at www.irs.gov) to the bank to open an account in the name of the estate with you as executor or administrator.  Deposit the check.  Pay the estate's bills, including taxes, from that account.