My Passport ultra 1TB not recognized by pc

my passport ultra 1 tb was working fine on windows 8.1
an hour ago it stopped showing on my pc tried it on windows  7 and xp and i got the same thing
the drive is spinning and the white light is on 
before it was flashing every 2 or 3 seconed but now always on 
so what happend 
i read on the manual that if the light is always on it means that the hard is ( idle ) 
so any help and any one know what happened ??

My 1TB is doing the same thing. A few days ago it just stopped being recognized by any device. I used my laptop, my father-in-laws laptop. The cord that comes with the HD, his cord that came with another HD. It used to be connected to my XBox 360, so I even reconnected it back to that. Absolutely no device recognizes that the HD is plugged into it.

It seems i’m not the only one with this problem :confused:
Hope someone can help 
I have a lot of files i don’t want to lose -_-