if its the front corner dropped most likely be just a broken coil spring ,[ but if its a back corner dropped most likely be a broken torsion bar ,luckily thats very rare .]
front springs break all the time ,they break easy due to poor quality and luckily arent very pricey to buy new . just look under the front wing and see if its broke daz . any spannerman worth his salt can change a spring in under an hour