The iTunes import dialog will tell you where it thinks the iTunes library is when you click the Advanced button.
Using Windows Explorer browse to the folder where the program thinks your iTunes is - this is where mine is - circled in red - and you can see it matches the location I posted previously
and the file you are looking for is circled in blue.
By default the iTunes library folder on your computer should be in the folder which will open if you click the Music link (arrowed in green above) in Windows Explorer.
If it is not there then you need to open iTunes and look at its program settings to find where it is storing the library folder, check the xml file is there using Windows Explorer and in MP3 Deluxe 19 point the iTunes import dialog option to the correct folder locationto this location.
It is very good of you to take the time and help me with this problem, I must admit I am at a loss to even find the iTunes import dialog or an Advanced button, can't see them anywhere perhaps you could point me in the right direction