OK I had BF1942 in my games library on Origin and, even though it was uninstalled, it’s allowed me to reinstall it there. If you don’t have that option, and don’t have the CD, there are versions out there which can be used. Also because there’s no gamespy or origin master server, I believe you can play without a valid cd key so long as you have entered something when installing it. As I’ve got a proper origin version though I’ve not been able to test alternatives, however I do also have two bf1942 cd’s and keys if necessary.