How Can I Recover My Files?

You have to give a lot more details before anyone can accurately assess what the problem is.

I'll take a wild guess. Let's say you wrote a story using the program Word. When you turned off your computer, you were asked by the program if you wanted to save it, and you picked Yes. If you don't know where it was saved to (a choice you set up beforehand), just start that program Word again. Then click on File (upper left corner) and you'll find listed the latest few files you created. Just pick the one that looks like the document you want to retrieve it.

You might try "Search" by clicking on Start then Search and when the window comes up look at the left and find and click on "All files and Folders".  When that window comes up on the left side, type in some word or words that are pertinent to your document.  Click on Search and documents containing the(ose) words will show up on the right.
If searching by multiple words, use the least amount of words as possible.  I would think this is the quickest way to locate a document.  When you see the document you need, make note of where it is located.  You can click on the document on the right side and it will open.