Reinstalling new fresh copy of windows using external dvd drive ?

ok.. i have a notebook that is unfortunately has a broken dvd drive that isnt working anymore ... i was a bit more frustrated now bcs i have to format my notebook, really need to format it . So, im planning to get an external dvd drive, not internal. but external dvd drive, so that i can formatted my notebook. so i went to a pc store and then they said u cannot formatted it using external dvd drive. so i brought my notebook to the store and they dont wanna do a test first ... that means u have to buy it 1st... pretty sucks ...but i got curios and post a question ... haha hope u guys can answer it .. really need helps here .... !!!