Problem with IPod Nano 4gb – please help me!!!

Hello, i’m having problems with my IPod nano. When I plugin the cable for Ipod into computer – ITunes shows me that my ipod name: IPod, capacity:N/A, Software version: N/A, serial number: N/A, Format: Windows.
But some time ago comp where showing everything except capacity. I just cant write any new songs on IPod, and i dont see what is on it.
Can someone help me and sorry for my english!