Question Cannot connect the hard disk

More information needed:

Make and model: hard disk, PC, laptop?

How are you making the connection?

What error messages, if any? If no error messages then what else does or does not happen?

Do you have another hard disk that you can try connecting to the PC? If a second hard disk "connection" fails then it could be the port or the PC.
 
Model: Samsung G2 Portable 500 GB

There's no error message whatsoever. And i didn't have other HD, but i've already tried flash disk, which is work very well