Following the theme of your other posts, what exact OS version are you asking about?
Further, it is up to the carriers to release change logs for the OS packages, as they hold the formal responsibility to certify and release OS levels to their customers. Sadly, most carriers do not release any information. So, you may have to do some digging.
Occam's Razor nearly always applies when troubleshooting technology issues!
If anyone has been helpful to you, please show your appreciation by clicking the button inside of their post. Please click here and read, along with the threads to which it links, for helpful information to guide you as you proceed. I always recommend that you treat your BlackBerry like any other computing device, including using a regular backup schedule...click here for an article with instructions.