You can only undete file as long as the diskspace they where on is not overwritten by other things. If it is overwritten you need a specialized company to do so. Use the search function on this board. Keywords = "handy recovery". I remember having posted a link to that freeware undelete program. It may also be in Bob3160's link list.
Other possible options:
1] If they are windows files, extract them from the windows cd.
2] If they are driver files, reinstall the drivers.
3] Perform an in-place repair of Windows.