What computer operating system is your Premiere Elements 12 going to be run on? I am assuming purchased for the same operating system, old and new.
If you purchased the product from Adobe, you can go to the Adobe web site, sign in with your Adobe ID and Password, go to Search and type in My Orders.
Then you follow the My Orders link to your Premiere Elements 12 order. There you should find the opportunity to download more installation files. Be careful to
select installation files that are consistent for your computer operating system and the order.
If you did not purchase from Adobe, you can download and install tryout files from the following and then insert your purchased serial number into them at installation.
Read and carryout carefully the "Note: Very Important Instructions" on the web page so that you do not run into any Access Denied message.
Do you have the purchased serial number. If you installed 12 when you purchased it, you should be able to find your serial number at the Adobe web site under "My Products".
Please let us know if you have any questions or need clarification.
Add On...You could also consider the Adobe Link - Other Downloads/Download Installers for Older Products (Premiere Elements 9, 10, 11, and 12.