Try repairing your battle.net launcher.
Click here for more info:
https://us.battle.net/support/en/article/repairing-blizzard-gamesYou can also reopen the battle.net launcher via your taskbar (bottom right corner).
If my launcher takes too long to pop up on my screen I simply double-click on the icon on my taskbar and it opens instantly.
This post was edited by ishpre on Feb 10 2016 08:23pm