What happens to a life insurance policy if there is no beneficiary??

Someone has died, and had a life insurance policy but didn't have anyone listed as a beneficiary. Before his death he did write a will of sorts saying that he wanted everything to be handled by his sister. So what happens to the life insurance, how does the sister find out where to go and what to do. Does she have to go get an Estate lawyer?? The insured also has a 17 year old daughter, so would it go to her since she is his daughter even though not listed as benificiary??