My printer isnt printing and its driving me nuts!!! ARG!

Its an HP Deskjet 990cxi and I have no idea whats wrong with it. I tell it to print and it just hangs there. No error message... just silence. Ive checked all the connections and the paper tray. Nothing is wrong as far as I can see hardware wise..... Someone please help me! Ive never had a problem with this printer untill now.... its been pretty loyal up until now.