WD 3TB external HD was working, now PC can't find (XP)

Hi all,

purchased a 3TB HD for file storage and plugged into PC running XP, all good, Plug and play worked…

Proceeded to transfer data from PC to HD and all OK for 2 days. went back to continue data transfer and PC now does not see HD.

Investigated and checked power (Light is on) replaced USB cable, still nothing. Plugged into laptop, (Vista) not found???

Please help, I have transferred data including family photos, not happy…

Bluejed

Try to check drive status on disk management.

Click start/ Right click my computer or computer/ click manage/ click disk management.

Is it detected there?Is it online or offline? Blue bar or black bar?