There are two ways ECDC4 can write to CDs.
1) Using Direct CD, and writing single files or bunches of files to a FORMATTED CD.
2) Using CD Creator and writing either a whole CD or at least a "session" to an UNFORMATTED CD.
Method 1 can be handy for local or short-term use, but the discs are unreadable on another machine unless you're running Direct CD on that machine too. Often they're unreadable unless you have the exact same environment as when you wrote them. Handy, but not over-practical or safe. Since you're having trouble I assume that you were using this method.
Method 2 is not so easy for dropping the odd file onto a CD, but it makes STANDARD CDROMs which can be read on any PC and many other machines.
Both methods can be used on either CD-R (write-once) or CD-RW (re-writeable) discs
If you want to archive precious stuff, use method 2 and write it onto a CD-R not a rewriteable CD. For very precious stuff write two CDs and store them in different places. Never trust your only copy of a precious file to a packet-written (formatted) disc.
Nero has similar systems. Their "InCD" is the equivalent of method 1, and the regular Nero writer uses method 2. Their StartSmart is a menu system, and Data CD should take you to the safe method 2.
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Right, that was how to archive them. Now, how to recover them from your old discs.
Various claims have been made about reading old Direct CD discs on new versions of the software, but the results (if any) have been patchy. They seem to rely on a combination of the new system, the new software, the new CD/DVD drive, and the way you hold your mouth.
I believe that your most reliable and least expensive solution is to get a recovery program such as CD Roller (www.cdroller.com) or ISO Buster (www.isobuster.com). These programs allow a trial so that you can see what files they can recover, though you need the paid version to actually do the recovery. Our forum members have recommended both of these recovery programs.
I wish you success.