My dad passed away last month, we have no knowledge of a will and my dad never discussed having a will. He has left behind a house which has about

You have indicated the estate has a value of about $80,000.00.  Certainly that would be enough to justify spending some money to preserve and divide up.  I understand from your comments that about $25,000 is owed on a mortgage.  You and your sibling should agree, if possible, on a way to keep the payments going so as to not lose the house to foreclosure.  In the meantime, confer with a good probate lawyer in your community.  He/she can help to locate the older sibling.  My guess is that he will be happy to participate some way if it means getting some money out of the situation.  If there was no will and no widow, your state law almost certainly would say that the 3 kids inherited the estate assets equally.  If you are required to make payments to preserve the house, and to pay for funeral, etc, I think you can be reimbursed eventually from estate assets.  Most likely, the house will be sold and the money from the sale would be available to pay costs first, reimburse you for necessary expenses, and then to be divided among the three of you.  The way to get it started is to confer with a good probate lawyer.