H5photography

I have a 3TB Seagate Desktop External HD; approx 2 yrs old that is now not being recognized by my computer. Tried on another PC, same results. When plugged in, the drive is powering up and making thr normal sounds. I've read that a lot of times, the USB board can go bad. I've tried a couple trial versions of recovery software to no avail as the HDD is not recongnized. Any recommemdations on who to send to (there's so many!)