you're referring to vi I take it?? please provide useful amoutns of informatino if you want help...
if it is vi, I think even without the original file this should work:
:rec[over] [file] Try to recover [file] from the swap file. If [file]
is not given use the file name for the current
buffer. The current contents of the buffer are lost.
This command fails if the buffer was modified.
Also it seems possible to just edit the file as if it was still there and it will automatically look for the backup