Adobe Premier 12 reinstall

I bought Premier Elements 12 some time ago, my hard drive had to be replaced and now I have to reinstall my programs.

I cannot find my Elements 12 package to reinstall the program.

I have the program on my system, I do the install set up and it asks me for my Serial Number which I don't have.

Questions:

1) Is there someway that I can get my serial number as I don't have my installation package/disks for Elements 12?

2) Can I upgrade to Elements 15 which I am happy to do without my elements 12 serial number as I have the program files on my  system?

Look forward to your response.