Follow these very important steps:
1. The first and most important thing to do is to stop using the computer you deleted the file from. Do not reboot it or switch it off. Do not save your files. Do not create any new files. Do not use your email program or a web browser. Do not logout of Windows. Do not defragment the drive.
2. If you have UndeleteOnClick already installed on your computer then run it and undelete the file. If UndeleteOnClick is on a an external drive, floppy disk, CD/DVD, Zip disk, network share, etc. then insert the external media and run UndeleteOnClick from it.
3. If you do not have UndeleteOnClick installed, on external media, or on a network share, then go to another computer and copy it to external media or a network share that the other computer can access. You can then go back to step 2.
4. If you don't have another computer you can use, and do not have it installed, on external media, or on a network share, then you'll need to download it and run it. If possible download it to a different drive from where the file was deleted.