Q: i forgot Apple ID

Dear Sir/Madam

i got a iPhone 5s as a gift from my relative who is working in Japan. unfortunately i have lost my phone and i got my phone, phone was locked and i forgot may Apple id, and sender also forgot id and its related other all information like security question. but we know the Apple password. in this case how can i unlock my iPhone 5s. please please help me i m in so trouble . this message will come when power on.