My external hard disk would not be reconized.

Hello,
I brought a new 1 TB seagate free-agent external hard drive. I connected it to my laptop which runs windows VISTA.
when i connected it for the first time, there was no problem in my laptop recognizing it or its ( wotever installation if you call it so ). so I transfered all my data as a back from my laptop ( aprx abt 100gb) to the new hard drive, and even double checked it on the new hard drive and everything was fine. later i disconnected the hard drive via the SAFELY remobe hardware. Later after abt half an hour I tried connecting back the hard drive to my same laptop, but it would not just show up. i tried everything liek trying to restart my system, connecting and disconnecting my external hard drive, changing the connecting USB cable, tried on different systems ( vista, XP) but the it would just not work( but the light on the hard drive does glow up). I ve noticed that for teh first few mintues( say 5-10 mins) there is some kind of slight sound from the hard drive Now all the data is on this hard drive and i am lost. I cannot affrord a data recovery options as its very expensive.
so i was just praying and hoping that someone could please help me out of this mess. Can someone out there please help me .

Regards.
Ravi.