CAN A BANK WITHHOLD CASHING A CHECK FOR SERVICES RENDERED? THE PERSON THAT WROTE THE CHECK UNEXPECTEDLY PASSED AWAY AND THE ACCT IS FROZEN.

The bank can't cash the check until the decedent's estate is settled, unfortunately.  This can be a lengthy process and may take place in Probate court, if their is a will, or in Surrogate's court, if the decedent has assets and no will.  Your brother should attempt to determine in which court the estate will be resolved so that he can notify the court that the estate owes a debt to him.  In that event, he should be notified by the attorneys seeking to settle the estate of an opportunity to obtain payment. I offer this information in an effort to allow you to better understand some general legal principals that may apply to your fact scenario.  This is not intended to substitute for a detailed consultation with an attorney.  Thus, the information above does not constitute legal advice.