.cda files are literally the directory of the music--note they're only 1 kb? So, you're not looking at the actual music files.
You thought you put mp3's on the cd, but the program that you used to burn them to the cd assumed that you wanted to make a music cd, so it converted the files to .cda. Use any one of the many free cd rippers out there to convert them back to mp3's.
Is this an Audio CD(you know, one you could play in a CD walkman, car or whatever) or just a disk filled up with MP3s?
The reason I ask is that you said these are 1kb files which is consistant with CDA. CDA files are located on Session 2 and are a shortcut to WAVs located in session 1 on an AUDIO Cd.
Is it just that the file extension is associated with the wrong program?