A file can be recovered or undeleted in its entirety right after it has been deleted, and for a fair while afterwards. But the chances of recovering the file intact decrease the longer you leave it. Because the longer you leave it, the more likely it is that Windows will reuse all or part of the file's disk space for something else. If you have defragmented the hard drive since the file was deleted, then unfortunately you have dealt a severe blow you your chances of a successful recovery.