I have a bb 8830 and i installed the new desktop software 4.3 last week and It isnt showing the media manager icon for me. I had the option selected and have uninstalled several times in attempt of resolving this issue.
You need to completely remove it, reinstall 4.2, then install 4.3 directly over top of it. 4.3 uses the Media Manager files from the 4.2 install, apparently. I did this, and it worked like a charm. Learn from my mistake.