great advice from gokuangel.....I agree. There are lots of vitamins. Also analyze your diet and other habits. Sometimes things like smoking or a poor diet or lack of exercise could be the cause....or if your taking meds for other health related issues, those could cause low counts in sperm as well. I'd see a Urologist to get a better opinion and to seek out treatment options.
im not sure bout prescription but if u would like u can try herbal remedies they do have one for the men that is supposed to help increase ur count and motility and u can even buy a sperm count kit at walgreens to test if the herbal medicine is working or not heres the site u can read the reviews on it u dont have to buy online they carry these at any health food store
http://www.evitamins.com/product_grid.asp?brandid=Michael's
in case this doesnt go where its supposed to the name is micheals reproductive factors for me.