My PC doesn't feel Nano Arduino when connected

I bought two nano arduino boards(generic made in china)
both of them i got in its electrostatic bag wrapping
one of them when i connect it the PC doesn't give any response
the other is OK
any explanation ??
any suggestion for solving this problem ??
thank you for help

(deleted)

Most of the CLONE nano require additional drivers.
That could be CP2102 or CH340/341

Ensure you have those installed.

THIS POST should also help you get the best out of the forums.

Bob.

If the PC does not recognise the one, I tend to agree with spycatchet2k.

i tend to beleive it is defective
i tried the two links sent by ballscrewbob and no change
thank you all