In the movie, the old man talking to young Star-Lord was not Star-Lord's Earth father, but his grandfather—his mother's father.
As for Star-Lord's Earth father?
Nothing was said. Maybe, like in the comics, he had died of heart disease, or maybe they had simply written him out to save on casting.
And judging from what Star-Lord's mother said before she died, it seemed her memories had not been erased. Unlike in the comics, Jason had not wiped her memories, or she would not have said anything about an "angel."
So Star-Lord's mother might not have married some Earth man like she had in the comics. In the movie version, she was very likely a single mother.
Well, for now, let's assume Star-Lord had an Earth dad.
Jim knew what Star-Lord wanted to ask, so he answered, "The house is still your family's, but... it belongs to your uncle now."
It took Star-Lord quite a while to understand what had happened.
A few years after he had been abducted into space, his father had died. Since he had no brothers or sisters, the first heir was gone. Naturally, the property passed to the second-tier heirs—siblings, grandparents, maternal grandparents, and the like.
So the house had gone to Star-Lord's grandfather.
His grandfather had promised his daughter that he would take good care of Star-Lord, but his daughter had barely died when his grandson vanished. He searched for nearly ten years, until the last of his strength was spent... and he died twenty years ago.
The house then passed once again to his grandfather's son—Star-Lord's uncle.
However, Star-Lord's uncle had somewhere else to live. He rarely stayed at this house in town, only coming down during vacations to relax.
That was the situation.
Star-Lord had no memory of his uncle at all. After