I needed to re-install CS3 web premium due to a problem. I downloaded the media but the set uprequired the original installation media which I never had due to originally downnloading CS3. How do I continue?

You do not need discs to install the software.

Download and Installation Help -

https://helpx.adobe.com/download-install.html

CS3 - http://helpx.adobe.com/creative-suite/kb/cs3-product-downloads.html

You can also download the trial version of the software thru the page linked below and then use your current serial number to activate it.

Be sure to follow the steps outlined in the Note: Very Important Instructions section on the download pages at this site and have cookies enabled in your browser or else the download will not work properly.

CS3 and CS4: http://prodesigntools.com/download-adobe-cs4-and-cs3-free-trials-here.html