Unfortunately I have had to replace a faulty HD and have lost all programs which were on the HD. I have tried to install the program on the new HD using the original disk (Audio Cleaning 12 Lab) with no success. As I am in the middle of a project, I need the program asap. Any help would be appreciated.
Which version of Windows did you have on the old HD and which on the new? ACL 12 (assuming you don't actually mean "Sound Forge ACL 1" [or later, up to 4]) may be incompatible with your new OS because it is now old!.
When you attempt the install, what error message do you see, if any? Please quote it in full or, better still, show us a screenshot of it.
Is there a possibility the program disc is damaged, or simply dirty? Can you "open" it to show a list of all its contents? If so, you could try creating a folder on your desktop, name it something like ACL 12 install and copy ALL the content of the disc into that folder. Then click on the actual installer (often called SetUp.exe or similar) and see if the program will now install.
If the disc is dirty try cleaning it using a clean, lint-free cloth, wiping from the middle of the disc outwards.
Audio Cleaning Lab 12 was released in 2001 and in addition to @emmrecs comment, the program was certified to run on Windows versions XP to 2000 which are very different to the 2 versions of Windows which are still supported by Microsoft.
If you have Windows 10 or 11 then if you manage to get it to install, it may not activate using the serial number.