use Frontline plus, it's the most effective for flea controls.

you can buy from online, usually you will see the result in 24 hours and it stays effective for a month. Dont' use flea collar from Walmart, or moth ball, or shave the cat. Flea collar and moth balls could be poisonous to cat, shave the coat off the cat is not a good idea because the coat is a protection for cats.
after you use Frontline Plus, the fleas in your carpet will soon disappear too.