Good day
You should only reformat your drive as a last resort. Start the anti-virus program and let it detect the infected file. Write down the path and filename displayed. Close the anti-virus program. Use My Computer or Windows Explorer to findthe file, using the info you wrote down, and try to delete it. If you can delete it, open Recycle bin and delete the file from there.
If you are unable to delete the file this way, use a file wiping utility such as BC Wipe or Eraser, both available from the web (and free), to wipe the file. These utilities actually overwrite the data contained within the file, permanently deleting it.
Another alternative is to visit an anti-virus web site such as Sophos or Symantec, search for the virus and see if there is a removal tool you can download which will automatically remove the virus, or see if there are instructions on how to manually remove it.
Good luck