Q: problem with iphone 4

You need to contact your friend and have him remove the device from his account.

You have to have the previous owner remove the device from their account

Find My iPhone Activation Lock: Removing a device from a previous owner’s account

Of necessary:

Is there a way to find my Apple ID Name if I can't remember it?

Yes. Visit My Apple ID and click Find your Apple ID. See Finding your Apple ID if you'd like more information.

How do I change or recover a forgotten Apple ID Password?

If you've forgotten your Apple ID Password or want to change it, go to My Apple ID and follow the instructions. SeeChanging your Apple ID password if you'd like more information.

Apple will not bypass the Activation Lock