Ruin, wreck, dilapidate can all mean to subject a person or more often a thing to forces that are destructive of soundness, worth, or usefulness.
Ruin usually suggests a bringing to an end the structural or mental integrity, the value, beauty, or the well-being of something or of someone through such destructive agencies as weather, age, or neglect, through partial destruction by fire, flood, or collision, or through loss of something vital to happiness or success (as one’s fortune, one’s good name, or one’s chastity).
Wreck implies a ruining by or as if by crashing or being shattered. Basically it is used in reference to a ship, a train, a vehicle, or an airplane.
In its extended sense wreck is often used in place of ruin when there is an intent to imply injury, often to something intangible such as one’s career, one’s credit, or one’s prospects, past all hope of repair or of reconstruction.
When the pulling down of a building is implied, wreck is often preferred to demolish or destroy because it does not necessarily carry the suggestion implicit in those words of the uselessness of that which is left.
Dilapidate historically implies ruin especially of a building, or of developed property, or of one’s fortune or financial resources through neglect or through wastefulness; the term in such use carries, as the other terms do not, a strong implication of culpability.
In more general use dilapidate implies a shabby, run-down, and often tumbledown condition and is used chiefly in the past-participial form as an adjective.