One of our readers had a problem with her android phone and asked us out to help her.
The problem was : She could not find her default messaging app in her Samsung Galaxy phone. We thought many of our other readers might also face the same problem in future and therefore we decided to address this issue publicly by writing a blog post.
The solution to this is simple. Just go to application manager -> all apps and scroll down entirely.
Sometimes due to some reason the application gets automatically disabled. It generally happens when you download a application similar to the default app.
Hope the post helped you.