My USB Harddrive can't be mounted (emergency help pls)

[oxiabit]

Hi. I have Seagate FreeAgent Go 250 GB USB Harddrive. I don't know why but I cannot access my drive. When i plug usb cable, nothing appears on desktop. Only Disk utility can see Drive. but it seems in grey font. when i click mount, it gives error that says repair disk. But when i start repair disk, nothing is happening. Progress bar is not moving. Just preparing bar like this

http://images.appleinsider.com/mba-series-2-080209-17.png

I am sorry about weak english but i have to access my drive and i dont know what to do. i need advise for this problem. I hope somebody can help me.

 

[r.j.s]

How long did you wait for the Repair to start?

 

[oxiabit]

Repair is not starting exactly. Progress bar show that rapair operation is preparing. but there is no more action except this. There is no time remaining information ( ex. 19 minutes ). I've waited almost 45 minutes. But as i said before nothing happened. finally an error appeard. it says Disk Utility stopped Repairing. Disk utility cant repair this drive. back up your files and restore bla bla bla.