If you deleted those files 3 weeks ago and you continued to use the hdd then the chance of recovery is slim.
Put the hdd in another machine or an enclosure and run recuva.....see what it finds.
I'm trying to recover some photos that I deleted from the recycling bin a few weeks before my PC crashed.
I'm planning on taking out the hard drive and putting it in a different pc or an external enclosure to get the files. Will the files show up automatically then or will I need to also use a recovery program like Recuva?