Hello,
[quote user="Sadok Guezguez"] it was running correctly since 2 months or more but yesterday i realised that i'm not able anymore to connect the board to the pc (i using printer cable )[/quote]
Have you tried using a new cable or different board?
Also take a look at Spectrum Digital's troubleshooting guide. I believe section 4 applies to your environment:
http://support.spectrumdigital.com/guides/troubleshooting_guide/
Thanks
ki