All files on a disk drive have a directory. Windows read a drive using its directory. When a file is deleted, it is removed from the directory so that Windows ignores it. However, the file is actually still in the disk. By using special softwares, you can find them and restore them.
To recover deleted files, you will need a software named 'PC Inspector File Recovery'. It can be downloaded from http://www.pcinspector.de/default.htm?language=1 . After downloading and installing it on your computer, run the software. This software works with hard disk drives, USB pendrives, floppy disks and memory cards (you must use a card reader). However, it does not work with any types of CD.
First, select a language and press tick. Click the button beside 'Recover deleted files'. Next, under 'Logical drive', select the disk drive where your file was deleted. Then, click the green tick button. The software will scan the disk drive and display a list of deleted files. Find your files inside the folder 'Deleted'. (The files in the folder 'Root' are the files which are not deleted. If you cannot access the disk from 'My Computer' you can try to access it here) When you found it, right click on it and click 'Save to'. Select a location to save the restored file.
Notice:
1. When a file is deleted, you should begin the restoration as soon as possible and do not create or save any new files. This is to prevent the deleted file from being overwritten. If the deleted file is overwrited, it will be lost forever and nothing can help you!
2. There is no 100% guarantee that the deleted file can always be restored. Therefore, you should always be careful.
3. If the disk drive is physically damaged and cannot be read by the computer, it is useless to use this software.
4. If the disk had been formatted or is corrupted, you may not be able to restore the files. PC Inspector File Recovery claims that the 'Find Lost Data' function can restore files on a formatted or corrupted drive, but I have tried it and it doesn't work. However, you may still give it a try.
If you want to delete a file permanently and make it completely impossible to restore it, then you should shred it. By shredding a file, the file is permanently deleted and cannot be restored using PC Inspector File Recovery or any file recovery software. Freeraser is a software that allows you to shred a file. Freeraser can be downloaded from http://www.codyssey.com/products/freeraser.html . After downloading, install it on your computer. To shred a file, open Freeraser. Right click on it and click 'Select file to destroy'. Select the file you want to shred and click 'Open'. Follow the on-screen instructions to shred the file.