Hi there manikumar249,
Is it a brand new drive? I see that there is no data on it right? If you don't have any data on it, you can delete these volumes and after that partition, format and assign letters to them.
How to partition and format:
http://wdc.custhelp.com/app/answers/detail/a_id/3865
Or you can start by trying to assign a letter to the current volumes through the Command Prompt. You can check how to do that here(second half):
http://technet.microsoft.com/en-us/library/cc757491(v=ws.10).aspx#BKMK_CMD
Hope this will help,
D_Know_WD