Go to finder in File up top hit new smart folder. Then Search downloads and you will see the download folder come up select and it will add to finder. Then add to dock. This may have been resolved but this is how I did it and it was easy.
THIS WORKS! I was in tears because I sent my downloads folder to the trash and then emptied it by accident. I do not have an external drive or have my computer backed up. I could not locate my folder anywhere and then I read this response and I was able to recover it! Thank you for such a simple solution!