Perhaps some people here could provide some guidance.
I’m afraid this person has lost a lot of faith in the Catholic Church after Vatican 2.
How do I help him? Are these feelings common with people who have experienced the change in the Church?
How can you blame him ?
"A day will come when the civilized world will deny its God, when the Church will doubt as Peter doubted. She will be tempted to believe that man has become God. In our churches, Christians will search in vain for the red lamp where God awaits them. Like Mary Magdalene, weeping before the empty tomb, they will ask, “Where have they taken him?” -Pope Pius XII
“Not to oppose error is to approve it, and not to defend truth is to suppress it, and indeed to neglect to confound evil men, when we can do it, is no less a sin than to encourage them.”
“What if some novel contagion seek to infect the whole Church, and not merely a small portion of it? Then he will take care to cling to antiquity, which cannot now be led astray by any novel deceit.” -St. Vincent of Lerins († 445)
“The day the Church abandons her universal tongue is the day before she returns to the catacombs.” -Pope Pius XII
“Even if Catholics faithful to Tradition are reduced to a handful, they are the ones who are the true Church of Jesus Christ.” - St. Athanasius, AD 373
“It is granted to few to recognize the true Church amid the darkness of so many schisms and heresies, and to fewer still so to love the truth which they have seen as to fly to its embrace.” -St. Robert Bellarmine
“In recent times, even in materialist North America, the growth of the Church was magnificent with the liturgy being kept in Latin. The attempts of the Protestants have failed, and Protestantism uses the vernacular. We ask again: Why the change, especially since changes in this matter involve many difficulties and great dangers? All of us here at the Council can recall the fundamental changes in the meaning of words in common use. Thus it follows that if the Sacred Liturgy were in the vernacular, the immutability of doctrine would be endangered.
The introduction of the vernacular should be separated from the action of the Mass. The Mass must remain as it is. Grave changes in the liturgy introduce grave changes in dogmata.”
-James Cardinal McIntyre addressing the Second Vatican Council.
“Tradition means giving votes to the most obscure of all classes, our ancestors. It is the democracy of the dead. Tradition refuses to submit to that arrogant oligarchy who merely happen to be walking around.”
“Indeed, the true friends of the people are neither revolutionaries, nor innovators: they are traditionalists.”
- Pope St. Pius X, Notre Charge Apostolique
Your friend has solid ground to stand on. Let him be a Catholic.