5w416 Modem No Worky For Me: Help

i think i did something to my internal modem (Dell Dimension 2400). NetZero doesn't work. System not finding modem. Can someone help me work thru the set up process on my Dell? (NetZero Internet works fine on this 98 Compaq!) So i think i need to reinstall something. My resource CDs have not helped. What can i do to ensure my internal modem is properly installed? 5w416 modem, V.92, data fax, internal, aluminum, Dell Americas Organization... Low Budget / Can't call Delllllll. What's my BPS supposed to be? I've tried 300, 9600. Never had dial-up. HELP!