Very Very Urgent - ISDN MODEM installation

Hello everyone!!!

Friends A very big problem is here so pls help me.

I have an ISDN Connection. From few days I am not able to connect it. There is no power in my USB MODEM also.

In device manager its not there. When I again Plug the USB Connector of MODEM after unpluging it, it found a device and I can install the driver.

But the problem is that after complete installation it says device can’t install properly because an instance of device already existing.

While I have already uninstall the modem many times.

Pls help me soon. Its very urgent.

thanks