A CD is composed of several zones
The SUA (System User Area) is composed of PCA and PMA.
Each session consists of
A track is composed of
Each block or sector have an header, the block location is stored in each header.
Photorec works well but bad sectors slows the recovery process.
It's possible to recover data from a quick-erased CD-RW disc without modifying it! When a CD-RW is fast erased, the PMA, TOC, pregap and the first sectors of your CD-RW are erased. Because the TOC has been erased, CD-RW appears as blank/empty. Because the first sectors has been erased including the headers, sectors 0, 1, 2... can't be located anymore but subsequent sectors can still be found. Unfortunatly, not each OS allows you to easilly access such sector but it works using Linux. To recover your lost data, run Linux version of Photorec. Start of the recovery is really slow because the first sectors are unreadable but usually after sector 300, data can be recovered, so be patient.
With multi-session cdrom, it is possible to delete files of previous session. Because the files are not really deleted, it is possible to recover them. To read files from the first session, run under Linux
mount /dev/cdrom /mnt/cdrom -t iso9660 -o session=0