Recovering trashed items

How can I recover items that may have been trashed and then the trash was emptied.

My husband was cleaning his desktop and said he moved our son's school file off the desk top to the documents file. It has completely disappeared. We have tried searching for it to no avail. I am afraid he trashed it unknowinly. Any suggestions? All our son's papers were in that file, along with his assignment that is due tomorrow!

Thanks,

EAJ