My m-audio not picking up sound...

Hey guys. I really hope someone can help me or point me in the right direction. I recently purchased an m-audio interface from Best Buy for my home studio. It's been working great until the other day when I began recording and it would not pick up a signal for my mic. I have another mic that connects directly to the computer via usb. So i tried that mic and got the same results....nothing being recorded. If anyone knows whats going on I would greatly appreciate it because I honestly don't even know the source of the problem.

Jerome

My mic is an Apex 435. I plug it into my m-audio fast track interface and that connects to my computer via usb connection.

Yes the phantom power is on. It was working fine just the other day...now all of a sudden the green signal light doesn't come on.

:-( i didn't want to hear that. It was in the back of my mind the whole time I was troubleshooting. Thanks for you help. I really appreciate it.