Some Muslims believe that in John 14 the reference to Helper, Advocate, or Counselor is a reference to Muhammad. Of course Christians hold that the Helper is the Holy Spirit. Muslims believe the text in John has been changed and that it should have "exalted one" instead of Helper. So they believe the exalted one refers to Muhammad. There is no evidence that the text in John 14 has been changed, but this is what many Muslims believe.
(John 14:16-17)"And I will ask the Father, and he will give you another Helper, to be with you forever, even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him, for he dwells with you and will be in you." (ESV)
Jesus did not ask the Father to send Muhammad to be with the disciples forever. In fact the Helper is even referred to as the Spirit of truth. The world did see and know Muhammad unlike the Holy Spirit. The disciples in the first century did not know Muhammad and he did not dwell with them because he was not born yet. One also wonders how Muhammad could be inside the disciples.
(John 14:26)"But the Helper, the Holy Spirit, whom the Father will send in my name, he will teach you all things and bring to your remembrance all that I have said to you." (ESV)
This verse directly refers to the Helper as the Holy Spirit. The Father did not send Muhammad in the name of Jesus to teach the disciples all things or to bring to their remembrance all he said to them.
Muslims who say the Helper in John 14 refers to Muhammad are practicing terrible and absurd interpretation, reading into the text things that are not there. Jesus did not predict the coming of a prophet who would supersede him. There is no greater prophet than Jesus. Of course Jesus is more than a prophet, he is the Christ, the Son of God.