The "Previous Versions" feature in Windows Vista is a major step forward for users, since it provides some built-in protection against losing important files. The problem is that the home versions of Vista don't give you an interface to access them, even though it's enabled by default!
Enter ShadowExplorer, a utility that runs on all versions of Vista and will let you access your "Shadow Copies", which are the internal backup copies of files that Vista stores every so often.
Recovering Files with Shadow Explorer
First launch ShadowExplorer as administrator by right-clicking on the entry in the start menu and choosing Run as Administrator. (Update:It should launch as administrator by default otherwise, but if it doesn't then use the right-click method)
The initial screen will show you a drop-down menu with the shadow copies of all partitions and disks you have.
Click on the last shadow (see the date) from THE DAY BEFORE the unfortunate event happened - make sure you get the right partition (most likely C: for your own files)
Since most of your files are in your User folder, double click C:\ then in the left pane choose "Users".
Then in the right pane double click the folder with YOUR NAME ( probably the last folder before desktop.ini). There you will find all your folders (and some more)
Now you can right-click on the folder or file you want to recover and EXPORT it to wherever you like on your system.
After clicking on Export, you'll be prompted for the directory you'd like to save the recovered files into.
Note that the Shadow Copies / Previous Versions feature is not a substitute for a proper backup solution, but can greatly help in a pinch.