Q: what if i cant contact the previous owner to get apple id and password

Then you can't activate or use that iPhone, but may be able to get a refund for it. The activation lock is an anti-theft measure; Apple won't unlock that iPhone for you.

(141530)

It requires the Apple ID and password of the previous owner. If you don't have it and cannot get it, then the device is useless to you. Return it for a refund, if you can, or take it to an Apple store for an exchange provided they will help you.

Find My iPhone Activation Lock

In the future check first before buying second hand: How to check for Activation Lock before buying a used iPhone.