I Want to develop a software that recovers deleted files from the disk as my final project assignment. How do i proceed? Would you please help me , you guys. Tell me the tools that i should use?

I usually recommend looking at an open source application that already provides the functionality that you want to implement....

http://www.cgsecurity.org/wiki/TestDisk

Thanks for the advice, but, i want to learn how it is developed and besides i am taking it as a final project. One of my courses is: Final project whis is worth 4 credit hour. I would appreciate if you could help me more .
looking forward to your post,
Have a nice time,

Isn't learning by example one of the best ways to learn? This is not such an easy thing to do and will require advanced understanding of several areas including the file system, the operating system and probably drive hardware. If you have a choice, a more simple project should be chosen as a course final. This sort of project could take months to develop. Start off with 'hello world' if possible.

How do you think i would learn from an already developed software unless i get the souce code of it?
I need your help how to do that?
looking forward to your post,

Filter already provided you with a link to said source code. Read the provided link and you will find the source code.

I have downloaded the source but i cant read it. I tried to open it using wordpad but it is really a mess.
The source file is: testdisk-6.5.tar
Which application program enables me to open it?
I am very grateful for all your helps.

http://www.rarlabs.com/ for example

Both IZarc (Win32) and 7-ZIP are free unlike WinRAR. (BTW, isn't 6.6 the latest stable version of TestDisk?)

I like to thankyou for all of your helps.
But, i couldnt see the source file.
There are a lot of folders in it
config - include executable files
darwin - includes readme file
doc_src - executable file
dos -readme file + .bat file
linux - executable files
src - a lot of text files (seems the source file but is unorganized . I dont know how i should read it)
win - readme files
doc - a lot of html files
If you know any small program that recovers a deleted file, please let me know. I was really scared when i saw the lots of files in the src folder.

Thankyou guys,