everyone looks great in their dresses! my black strapless dress has arrived but i'm so bummed out about it. I was so excited to try it on but I think it’s a little small for me or there's something wrong with the dress because the zipper came off.

it came off one side of the dress and then when I tried to fix it, the entire zipper head came off. I tried to put it back one but it looks like theres no opening to put it on. does anyone have an advice on what i can do? is this fixable or do i need to replace the entire zipper? also has anyone replaced the zipper before and how much would that usually cost?