Copyright law

If you are using someone else copyright protected work without prior permission from that person then it is a clear infringment of his or her copyright.

You need to contact that person (whom the work belongs) for permitting you to use his work. That person can be the person who has created that work or the one who has the rights over this person, i.e. to whom the original creater has surrendered his or her rights.

If you use the work without any permission then the person who  can take an action against you can only be the person who owns it and not anybody else. So if you are using that work for a private use, which in no way would be known to the original owner then it is not a much problem. But it will be still defined as infringment of a Copyright.