Antique Painting With No Signature

So to start the painting is very old and has no signature. I have owned it for 40 years myself and the painting was already extremely old when I came across it. The frame fell apart right when I picked it up. The canvas is very very dark yellow almost turning to a brownish yellow. It has about 8 nails on each side holding the canvas on it has a wooden shims stretching the canvas I would like to know anything I can about it like the date it was made generally, The artist who painted it, what style it is, where it comes from  it is 15” Tall and 12” WideI tried to explain it the best I could please let me know anything you can thank you very much