It's tough to believe that a 21 year old has no libido, is he on any kind of medication such as an antidepressant? Usually meds like Prozac can virtually kill an individual's libido. Maybe he IS depressed in some way and this is the cause of the lack of sex drive? The weird thing is that he admits he may have a problem. How is his diet? Diet can be a huge factor and poor diets can lead to failings libidos. I'd check the diet and maybe get him on some testosterone boosters such as Tribulus - his libido will go through the roof. Check out herbal sex enchancing products as well, some work amazingily well.