Father died; brother/landlord taking all assets

I am not admitted in New Hampshire.  I am sorry for your loss.

Did your Father have a Will?  If he did not then he died "intestate" and under most state's intestacy laws your Mother and you would inherit, not your Uncle. 

Either you or your Mother needs to be appointed as personal representative of your Father's estate ASAP.  Once appointed you will, be given powers under the law to do whatever is necessary to gather your Father's assets and debts, including bringing suit against someone who took something from the estate improperly.  Get legal help if you can.  Good luck.