Conrad, please check the audio folder for the project you are working with. Bouncing a clip/track applies effects to the audio and creates a new clip ("destructive"); however, SONAR does not delete the original audio wave file that was created. Most likely you still have that audio file (which is also why I manually save prior to destructive edits).
There are a couple things to try... Try adding a new audio track to the project, then right click and "Import audio"... drill into the Audio subfolder and look for the track number/name of the wav file you inadvertently bounced... these are numbered sequentially in (), so pick one with a lower number. Also, with project saves, you should be able to open an earlier version of the project.