Bows and guns

As the others have said, Dmar, make sure you have ammo in the ammo slot and that you are using the ability "shoot" in your hotbar.

How do I use my ranged weapon?
http://us.blizzard.com/support/article.xml?locale=en_US&articleId=19882

Also make sure that your bow or gun is repaired, if its durability is at zero you won't be able to use it.