Windows 7: Media is Write Protected

Dear All:
I have Sony Vaio cr410e with windows 7 ultimate 32 bit installed
I have external hard Western Digital WD 1 T.B
my problem is that my hard was working properly and suddenly my windows is unable to detect it when I connect it, I can see the icon of usb device in the task bar but I can not see my hard partitions in My computer. I tried to check it in computer management section I could see it there but it says that it is unallocated and when I press right click all options are inactive except for properties and help.
I tried to update the driver and it says that I have the latest version installed.
also I tried to make it offline under the computer management section I got the message that "the media is write protected".
I need your urgent help cause I have important data that is crucial for my job and my whole life.
waiting your response ASAP

i hate external drives that require software to run. unless its only drivers you updated.

now if it were a desktop id suggest taking the HDD out and sticking it in your pc.. but thats an issue here.

If you have another computer to try it on then i suggest trying that. When ever ive had the old "write protected" issue its normally only been with flash drives and its because they are duff.

Also as an after thought, a system restore to a date when it worked may pay off, but its probably a long shot

thanks dear I will try your solution to see if it will work. However I forget to write in my post that I tried to connect it on other computers with different operating systems like xp and I had the same problem so I think that system restore will not sole the problem
thanks again