Connection problem with Sony external hard drive

Hello,

I have Sony an external hard drive, was OK for 5 month's. but after that, become useless, the connection between laptop and drive is suddenly disconnecting in between. I thought it is problem of connecting cable so I changed the USB cable and no result as well, the drive get connected and suddenly it loosing its contact with PC/ laptop. I tried to using different PC, but no result.
Please guide what to do.
Regards