You can bring a legal action which was traditionally called an action for an "accounting" in which, as an heir and so someone who has a legitimate, legally recognized interest in the "estate (your mother's assets), you ask the court to make the executor "account for" his actions as executor. If he has not followed the will (executors *must* obey the will), if he has not been honest or loyal to the heirs' interests, if he has improperly diverted money to himself, or if he has been well-meaning but incompetent, a court can order him to do certain things (like return assets to the estate, or pay out of pocket to compensate the estate for value he has lost or taken) or can replace him as executor. The executor's duty of loyalty and competence is called a "fiduciary duty"; when an executor breaches it, a court can take action. If you wish to explore this option, consult wiht a probate attorney: this can be a procedurally complicated action (certainly compared to, say, a small claims case), and it is not recommended that a nonlawyer tries to bring this him/herself.