Lolita is filled with symbols, although few are archetypal. First, let's consider what an archetypal image/symbol is. According enotes.com, an archetype "is an original model of a person, ideal example, or a prototype upon which others are copied, patterned, or emulated; a symbol universally recognized by all. In psychology, an archetype is...
a model of a person, personality, or behavior." Archetypes connects the reader to the text because they make a storyline more familiar. For example, Thus most authors will use them.
However, Nabokov uses more straightforward symbols throughout the text. Rain/water is a recurring symbol in Lolita. This could be archetypal because it prompts some of our most ancestral memories. Rain can both cleanse and dirty. It can also restore or destroy. For example, when Humbert first goes swimming with Charlotte in Part One of the novel, it is a refreshing experience for her. However, all Humbert can think of is how easily he could drown her and not be caught, thus leaving him in sole custody of their shared daughter, Lolita.
Fog and the color gray are used to convey confusion. In Part Two of the novel, Humbert is driving with Lolita when he believes that they are being followed by a detective. However, Humbert is unsure if it is really or happening or if he is losing his mind. He refers to gray colors throughout the experience. In addition, when Humbert is prepared to meet Lolita again towards the end of the novel, he finds himself traveling through fog, conveying his his lack of mental lucidity.
In short, the symbols used in Lolita help convey the mood and atmosphere of the story.