dou = all ye = too Shenme dou bu zhidao. = doesn't know anything = all doesn't knoe Shenme ye bu xiang chi. = doeasn't want to eat anything = anything also doesn't want to eat.

都 dou1 (adv) Means:all,just because of,even,already 1.这"都"是些什么? What's "all" this? 2.你们"都"会开车吗？ Can you "both" drive? 3.你的酒沾"都"没沾。 You haven't "even" touched your wine. 4.你把钱"都"花了吗？ Have you "already" spent your money? 都 du1 (n) Means:capital,big city,metropolis,a surname 1.开罗是埃及的"都门"。 Cairo is the "capital" of egypt. 2.上海是一座闻名全世界的商业之"都"。 Shanghai is a world-renowned commercial "metropolis". 也 ye3 (adv.n) Means: adv:also,too,as well as n:a surname 1.你"也"会弹钢琴？ You play piano "too"? 2.现在我"也"受到痛苦。 Now I "also" suffered. 3.他懂英语"也"懂德语。 He knows german "as well as" english. 4.星期日"也"要上学。 We go to school every day "besides" sunday. 5.以前找得出，这次"也"行。 We got it before. We'll get it "again". English can never explain Chinese vividly.

(dou) : generally,it has three means.1, all 2.even 3.already (ye): 1: the same thing 2.the same result 3.even 4.euphemistic In degree , (dou)'s tone is strong than (ye), but sometimes, they can exchange, coz they have the same means. In your example, I think they can exchange,both ok.For tone , (dou) is power than (ye)