Trouble Opening CS 5 after copying folder back to iMac post reformatting hard drive

Not every program can be migrated by copying over the installed folder on a Mac. During installation some programs copy/write files at different locations which you might be unaware of and hence did not copy over, so the program breaks. Adobe applications fall in this category, you can't copy them over. Nancy has provided you the steps that you should try, in addition i would suggest you make sure the OS on which you are trying to install is the recommend version else there is no guarantee the app will run properly

-Manan

That almost never works.

First remove old CS files with the Adobe Cleaner tool. 

https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html

Next re-install with your original disks or downloads.   The installation routine is necessary to edit high registry system files.  Otherwise, you can't use your software.

If you forgot your serial number, you might find it in your Account Portal.

Please log-in to your account below.

https://account.adobe.com/products