If we have no communication from sister, the executor of my mother’s will, what recourse do we have?

Has she been appointed by the court to be the administrator of the Will; being named in the Will gives you almost no actual power. Tell her if she does not contact everyone within the next 5 days you will file to probate the Will and have someone else appointed to handle the distributions. If she was appointed by the court, tell her she is legally required to provide certain information and if she does not you will ask the court to appoint someone else.

If you are a beneficiary under the will, you are entitled to a copy. If sister is in possession of the will, she should have lodged it with the clerk of the Superior Court in the county of residence of mom, and she should, by now, have filed a petition for probate. Check with the court clerk; he or she can check by mom's name. If no lodging or filing, see a probate lawyer, who can stir things up by filing a petition with the court.