you may try Coat hair cover with disposable shower cap leave on over night. In the AM put shampoo on hair before you wet it! Wash twice castor oil is gone and so are lice. do comb hair carefully to be sure there aren't any nits left.
After you use the product called Nix, it's very important that you take a comb and sit outside if possible with natural sunlight or sit inside near a sunny window and comb through hair slowly, looking for any lice eggs that are still attached to the hair strand. You then literally have to use your fingernails to pull that sticky egg all the way down and off the strand of hair. If you don't follow this step, the lice will return shortly!
use a reliable headlice treatment. follow the instructions thoroughly. comb with a nit comb afterwards, make sure you have conditioner in the hair to comb. when its clean and dry, pick any eggs out by hand, that the comb didn't get. repeat the process in 1wk. now to prevent them; get a spray bottle, mix 100% oils of tea tree & eucalyptus in with conditioner and water. spray her hair daily. you'll need no more than 10 drops of each oil.
Without knowing your youngin's age, hair dye! An over the counter, inexpensive hair dye. Not only does it kill everything (lice & eggs) it works to prevent reinfestation. You also need to launder all clothing & bedding. My heart goes out to you! Take comfort, there is life after lice! =)