Version 17 is now very old; the current one is 27, so I strongly suspect your chances of being able to access any download is next to non-existent, sorry!
However, do remember that the current version, 27, exists as Plus, Premium and Free variants. Choosing to install the latter and then entering the serial number for your previous version 17 (assuming you still have that number) should allow you to access as many of the instruments, soundpools etc., from 17 that are still available to you. See this page for details of how to download the current free version.
MAGIX would no longer be stocking any replacement discs for this old version. However, if you at least still have your serial number, you'd be able to download the installer from the MAGIX website. In fact, if you registered your serial number, the installer download would appear within your account on the website ("Service Center"). Here are the relevant links for your convenience: