I can't see the pieces

I cant see the pieces of the chess when I try to play. Why?

Maybe you activated by accident the blindfold mode?
You find it in "Preferences => Game Display => Blindfold Chess (invisible pieces)
lichess.org/account/preferences/game-display
it's the last Option

Do you see the pieces of other Players playing?

@Sputnik_Monroe makes good points. Do you see the pieces on the boards at lichess.org home screen?