i cant unlock my iphone

It seems like that this iPhone is activation locked to another Apple ID, so not the Apple ID that you're trying to unlock it with.

If it is activation locked to a previous Apple ID of yours which you don't have access to anymore, and you're the original owner of the iPhone, and you have valid proof of purchase information, you can start an Activation Lock support request.

If the iPhone is locked to someone else's Apple ID, you will need to contact them to remove the lock. Activation lock is one of the best theft deterrent systems out there, and Apple will not help you remove the lock if you're not the original owner.