no sound

Hi, using my Super usb Cassette capture on audacity to record cassetted to mp3 files.
Worked fine yesterday, but today everything looks the same on screen. but no recording, no sound, just a straight blue line on both speakers
not a computer wiz, so please dumb it down for me.

Ensure that the Super usb Cassette is connected to the computer before you launch Audacity.

Then launch Audacity, and ensure that the in the device toolbar the recording device is set to the USB device, and the playback device is set to your normal sound card.