Question

قدیما وقتی کسی میخواست بره مهمونی خونه ی کسی.... از قبل خبر نمیداد 

یه دفعه میرفت خونه ی اون فرد 

Answer 1

The distant past(in the old days/in days of yore) if anybody(anyone) supposed to go someone's home for the party.....[they] would not inform you earlier

[they] would go to someone's home suddenly and unexpectedly  

Answer 2

In the past, when somebody wanted to go to someone's home, they didn't tell them (that they wanted to go); they just went abruptly.