The lice killing medicated shampoos DO work but you can't just use it & expect it to go away. You have to properly rid your house & everything in it of lice at the same time you treat every persons hair.
It is very hard to remove lice on your own head. Get a lice comb and have someone go through your hair strand by strand looking for nits (lice eggs). In bigger cities there are people who do this professionally. You want someone who is really good at spotting nits. The shampoos really don't work very well. The lice seem to have developed resistance. Maybe some people have had good results with shampoo but my results have been poor, even when following the instructions to the letter.