Lightroom 6 lost after pc crash; how to re-install without installation-cd

After a pc crash we lost our lightroom 6 program. We have a lenovo-laptop, windows 10.

Problem is that we cannot find our installation-cd; don't seem to find were we hid it...

We can find our serialnumber back in our adobe-id, registrated products.

we tried to download a trial lightroom CC in order to try to put our serialnumber/licensenumber to re-activate a lightroom 6 version; but that didn't seem to work.

Can anyone help us with this?

How can we restore our lightroom 6; how to reactivate this?

thanks in advance!

grtz.

Tina