Those old standalone versions that were activated by a serial number are no longer available from Adobe and are no longer supported nor updated by Adobe. If you don't have the installation disk it's unlikely that you will be able to find the software to install. IF you are using a Mac computer and are using the newer operating system you won't be able to install it anyway because the installer is 32-bit and the newer Mac operating systems will not run the installer.
Added later: I see under the heading of Topics that apparently you are using Windows. There are links where, if you still have your serial number, certain older versions can be downloaded from third-party resources. What version are you looking for?