The defender came in for criticism over his leadership of the Brazilian team at their home tournament, which culminated in a 7-1 semi-final defeat to eventual champions Germany.
And Blanc believes the experience is still having an adverse effect on Silva's performances.
"He doesn't speak about the World Cup," said the PSG boss ahead of Sunday's Ligue 1 trip to Guingamp. "But you can be affected by something without having to talk about it.
"That's a bad period during his career. He knows about it. We all had to go through a phase like that, you just have to be able to keep going forward.
"The most important thing is that the technical staff, and more importantly the head coach, help him to go through that.
"The environment is not going to help him. It needs to be him, the players, the head coach and the club who have to help him.
"He will then be able to come back to his level of performance. Easy."
PSG suffered their first defeat in all competitions since May when they lost 3-1 to Barcelona in the UEFA Champions League on Wednesday.
Asked whether he felt any pressure following the loss, Blanc said: "There is always a risk. Of course there is more after your first defeat in seven months.
"In seven months, one defeat. Honestly, even If my president would like no defeat at all, for one in seven months I would sign straight away for the same thing over the next seven months."
