So i think there is a problem

so i just finished some mid terms, decided to crack open my carboy which has been sitting around for the passed 3ish weeks and see whats up
i used 5 liters of canned apple juice, threw in around around 2 cups of brown sugar some tablet stuff. not sure if it is supposed to still be really really sweet, but it seems like there isn't much alcohol in it at all, what could I of done wrong?i used white wine yeast, not sure what strand, the airlock wasn't bubbling a whole lot, but i figured that could be due to the large volume of air compared to small volume of liquid in the carboy. not to sure what to say, i think it is probably spoiled. any suggestions?

did your fermentation start?? what are your Specific gravity numbers??

any airlock activity?

5 liters = 1.3 US gallons. What size carbouy did you put this 5 liters into? What was your OG? What is the current SG? What is the "tablet stuff" you mentioned? Did you check the label on your canned juice to see if it contained any preservatives? I don't mean to hammer you with questions, but without this sort of info, it's going to be pretty tough to figure out what the problem is. Regards, GF.