Are you referring to the farm located in Øvre Eiker district of Buskerud which in 1900, 1910 and 1950 was called "Sønju", earlier in 1865 was called "Synju", and in 1801 was "Synje"?
Without identifying the correct area in Norway any research will be almost impossible.
Your posting said only --
"Ole Sonju Helgerson
He was born in 1815 in Norway. He married Ingebor Marie Gulbrandsdatter in Norway. That is all the information that i have. as far as i know, he is as far back in my family as i can go. i would love any help on him, his relatives, his wife. i would also like to know if the home Sonju Farm is still standing."