When you delete a file, all the pc does is take out the entry in it's file location system, but there is a second copy of this on the hard disk for emergencies, and an undelete program looks at this, then checks the file location to see if the data's still there, or has been overwritten, and as each entry has a link to the next entry, it knows where to keep looking for the data.
But as JohnD says, if you load a program, then you risk overwriting the files that you are trying to recover, so you need an undelete program that can work from it's installation disk, so do you have an external cd writer with the nextbook, if not, then take it to a specialist who'll hook it up to another computer, and read it as a slave drive. Alternatively, can you connect it to another pc via a usb cable, and get the other pc to treat it as an external drive.