That's odd.. nothing happens at all when you use the "use force" key (with the force power selected using the "next/prev" force power keys)?
Can you see your HUD? There should be a little thing on lower right side of the screen showing the amount of ammo you have, batteries/field light, plus a red/orange globe that represents your force mana.
If this is solid black, it means you are out of mana and cannot use a force power. However if you ATTEMPT to, the text should appear at the top of the screen showing the power you tried to use.
I would check to be sure you have the force power again (hit esc and go into Force Powers and make sure you have stars assigned), also be sure you have your keys bound correctly. It should at least show the text above proving you tried to use the power..