Bought second hand iPhone 4s but can not get passed the apple id and password tried using my id account but nothing

Bought a second hand iPhone 4s and can not get passed the apple id and password from previous owner, I've tried using my apple id and password but nothing, the person I bought this phone and a few others from has a job lot does not no anything he bought loads of different electrical items has a big job lot, I've got the imei number and the ios version, used the imei checker website and says the phone is not stolen or anything like that just wanted to buy my daughter a iPhone for her birthday, that's all she keeps going on about, iam not working and a single parent trying to just get by in life, can anyone help me, thanks