What exact hardware are you using. (Make+model of mic and/or interface, types of cable, anything in the chain)
You say you're recording instruments. Does that mean DI guitar/bass, or are you using a microphone?
Is it a keyboard over line input?
Did it ever work? Is any of the gear new?
Have you installed any necessary drivers?
Does your hardware show up in windows as a device? Does mixcraft identify it by name?
Are you monitors plugged into your recording hardware? Can you listen to music in itunes/media player, etc?