I am sorry to say that you will almost certainly need to begin retyping.
The rest of the discussion in this Comment would best be categorized in the "grasping at straws" or "what to do next time" department.
If you had AutoRecover enabled (using the Tools...Options...Save menu item), there would be a backup copy in
C:\Documents and Settings\your Windows log-in name\Application Data\Microsoft\Word
until you close Word. There may also be a backup copy in the same folder as the original file (manoj); if so, its name will be something like ~paper.doc. As part of closing, Word deletes these backup copies.
But if you had the presence of mind to use Task Manager to force quit Word (or pulled the plug on your computer). Then the backup copy will still be there the next time Word launches. It is worth noting that the Application Settings folder is hidden by default--so you won't be able to see it unless you choose the option to "Show hidden files and folders" in Windows Explorer's Tools...Folder Options... View menu item.
A file undelete, might be able to recover your data--assuming that you haven't used Word since wiping your document and that you had AutoRecover enabled. If you find any, recover them all and change the suffix to .xls. You can then open them one at a time to see if you can recover your work.
If you saved your file on top of another file, you may be able to recover it by double-clicking your Recycle bin. Your file may be there.
When you saved the file, you didn't actually wipe out the old file. Rather, you erased its entry in the file allocation table. What happens is that Word or Excel saves the file with a random file name in an unused part of your hard drive. If the save is successful, it renames the saved copy with your desired file name--and erases any other mention of that file name in the same folder in the file allocation table. So if you can recover the file contents before those file clusters get rewritten, then the day will be saved.