I cannot find the box that i downloaded from. once someone told me how to move my lightroom from my hard drive. otherwise, you could tell me how to move it from my old computer. I cannot find my serial number
Please get the terminology correct
Download is to get something from the internet. You download something from a website or FTP server using a Web Browser or FTP client.
Install is to put a program you either bought at a store or Downloaded from the internet onto your computer hard drive so you can open and use it.
These are 2 totally different things.
Downloading a program from the internet does not Install that program on your computer.
If you still have your old computer you can get the serial number from the hard drive.
Review this Adobe web page for the exact location of where to look for the serial number.