Hi there, I just had this problem recently. You should be able to go to the adobe site and download the program using your product key. That's what I did for all of the software I had. For Lightroom and Photoshop though, I just signed up for the Creative Cloud for $9.99 a month and you automatically get the latest updated versions etc. Loving it tbh!
I thought all computers had a disk drive (or equivalent) - what am I missing?
If you mean "optical disk drive" (CD/DVD) then I'd say: "It's rarely a good idea to install Lightroom from CD/DVD even if they have such a drive" - you always want the latest, and what's on the disk rarely is..
I guess they d all have disc drive. Is been a long day.
Sent from my Verizon Wireless 4G LTE DROID
He did use the term "disc" not "disk". For me the C version is optical media and the K version is a hard-drive.
To answer the original question, you can download the latest LR 5.6 update and then enter your serial number. The LR updates, along with most other Adobe updates, are available here: