Welcome to the forum!
Unfortunately the cwb-files are much more vulnerable than cwp-files. They should not be used as the only saving mode, but mainly used temporarily when moving projects between computers.
If the cwb-file gets corrupt, there's little to do. The audio files of cwp-files are still there, if something goes wrong, and AFAIK also the whole file structure is more "durable".
And like the wise guys here say:" If you don't have the project in three places, you don't have it." Backing up regularily, often enough, is an essential habit to learn. If you have backups, try them. Also, if you have an earlier
version of SONAR, you could try that. Even downloading a demo of some CW software and trying to load the project there would be something I'd try if nothing else helps.
You say: "My projects have lost audio.." Do you mean all your projects are messed??