Brother died without a will

The death certificate does not prove you have a right to his money: he may have willed it to someone else; he may have a spouse or child who would inherit ahead of you if there is no will; there may be some executor or personal representative appointed by a court who has the legal authority over your brother's "estate" (the money, property, belongings, and other assets he left behind); etc. All the death certificate shows is that your brother died.
You need to go to the courts and apply to be appointed the estate's personal representative: if he had no will naming an excutor and no spouse or child applying for the role, you should be appointed. That will give you the legal authority to control his account and access it for certain proper purposes (to pay his final expenses or debts; to pay amounts, like a mortgage or taxes or car loan, required to preserve his belongings pending their distribution) pending distribution to heirs. Then you need to go through the probate process to have a legal determination of who will inherit from your brother (which may be you, but if it is or is not depends on what other relatives there are and if he had a will). Contact the clerk of the probate court to inquire about applying to be the personal representative and start the probate process.