If you purchased discs your account will not have links for downloading, but you can download thru the page linked below.
You will need your serial numbers. If you registered the softrware when you originally installed it then you should be able to find the serial numbers in your Adobe account online.
CS5 - http://helpx.adobe.com/creative-suite/kb/cs5-product-downloads.html
If you really do mean Elements 4 there is no download for that old of a version. Version 7 is as far back as you can go.
