It couldn't have taken that long. If I remember correctly, the way Windows "deletes" files is by prefixing a special character (I believe an upside down $) onto the file name. This tells the operating system to hide the file from the user and makes the space used by the file available to the operating system to be overwritten. There are a number of free utilities that can very quickly scan the drive for "deleted" files marked by the special character. It would only take a few minutes to recover in the best of circumstances and potentially a few days if the file was corrupted or had missing pieces.
If the owner of the file were smart he would have deleted the file by overwriting the section of the hard drive with random data several times. There are free utilities that do this and it would make recovery nearly impossible.