All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Magic is a reality and has a real effect on the bewitched person. It is mentioned in many chapters of the Quran like Al-Baqarah, Yoonus, Taha, Al-Anbiyaa’ and others.
As to your question about methods for knowing magic spells, if you mean the symptoms of magic that can be seen on the bewitched person, then some of its symptoms are:
However, if you mean to ask about methods for knowing where the magic spell is hidden, or for identifying the one who has worked the magic, these things are impossible to be known. If someone claims to know this, then he is either a liar or he is dealing with the Jinn and, in this case, it is permissible to turn to him for help.
Allaah Knows best.