Check out the Total Immersion method. Though I was a lifeguard and WSI, I never learned how to really swim, that is to swim competitively. It wasn't until I purchased the book and DVD Triathlon Swimming Made Easy and worked through the progression of drills that I trained my body and develop the muscle memory to be able to breathe on both the right and the left and to relax in the water. It took me several months to learn to swim again but it has been well worth it.

http://www.totalimmersion.net/

The key is to practice, practice, practice!