Really you need to locate the original download as there is no download link for Rh10 from Adobe's site. Whilst vendors will still have boxed sets, they will not have trial versions and you will not want to pay for a licence.
If you cannot trace the media, you will need to find proof of purchase. With that to hand, contact Customer Support as I believe in that scenario they can provide a one-off download.
There are several 'tricks' to download the old, offical versions of
almost all of Adobe's software. You can download the official RH7-10
versions from Adobe.
The following link lists how to download the official old versions. You
will install a trial or will need to buy a licensce code for the correct
version. These versions are 100% legal.
for download instructions. Make sure to follow the instructions to the
letter, otherwise your download won't work.
One note, the download link provided on the page above only lists RH8.
But just copy the download link, change the version number and you're
good to go.
(Also works for old versions of TCS/FrameMaker/Captivate/etc.)