Why won't your technic launcher work?

Well I would need more details, you can head over to the "Questions" part of the new Technic Pack website (technicpack.net) but here are some fixes to widely seen problems:

White screen on first startup of game: One thing to check is your LWJGL, a collection of code known as a library that Technic will use. Download the latest version from LWJGL and go into your .techniclauncher folder, accessible via typing in %appdata% in RUN (Windows) or manually typing in "/.techniclauncher" after your user base folder (your username's home on Linux or the folder Finder starts up with in Mac).

Problem starting launcher: Try using the .jar launcher instead of the .exe, and if that doesn't work, or you're already using the .jar, redownload the launcher. If that still doesn't work, update your Java to the latest version.

Linux

Problem running game: Make sure you don't have any added mods, files, texture packs, etc to the Technic game. Also make sure you're running the "Recommended" version opposed to the latest. Check that by going into Options in the launcher. If all that doesn't work, go to your .techniclauncher (instructions in first answer) and deleting your mod pack folder. Then redownload the mod pack from the launcher.

If any of the above did not work, try updating Java, updating LWJGL, Redownloading, and Redownloading game data. Get further help by going to the questions in technicpack.net and asking your question.