PLEASE HELP!!! (SIMS 3 Launcher won't open on MAC)

If you can't get it working by resetting RAM, I would recommend that you cleanly uninstall the TS3 game and associated files from your computer, then install the base game and patch it with the manual superpatch. Instructions for doing this correctly are below in sections 1 and 2. If you wish to use Origin, also see the additional guidance in section 3 below.

1. Clean uninstall and reinstall

When you uninstall TS3 games on your Mac using the uninstaller, the game leaves behind stray files and isn't completely removed from your computer. These files may conflict with future installations. It is best to completely remove them. BluebellFlora's website provides a guide on how to do this:

http://bluebellflora.com/the-sims-3-on-a-mac/how-to-do-a-clean-uninstall-and-reinstall-on-a-mac/

After cleanly uninstalling, install the base game and patch it up to date. If you cannot update via the Launcher, download and apply the latest cumulative manual patch (called the superpatch) for Mac. Be sure to choose the right file - there are various 'regional' files for disc-users and one designated region 7 for Origin-users.

Check that your game works properly. Then install any EPs and SPs that you own, in order of release date.

2. Further information on the cumulative manual superpatch

Many simmers find that patching their game via the Game Updates tab of the Launcher does not work properly. It is then better to download and apply the manual superpatch. It is important to download the Mac version rather than the PC version, and to pick the right one for your region. Be aware that if you are using a disc you need to choose the correct 'regional' file but if you are using digital download through Origin then you should use the file designated 'region 7'.

Instructions and the links to the downloads can be found in the Mac section of the forums at thesims.com here:

http://forums.thesims.com/en_US/discussion/549552/official-ea-download-links-for-the-sims-3-cumulative-manual-update

If you use any mods or custom content, be sure to remove them before patching.

3. Using Origin to install games on Mac

Download and install the Origin client for Mac and make sure it is up-to-date. If you already have Origin on your Mac but are having problems with downloading or installing games, delete the client and download a new copy (this sometimes fixes issues with downloading). The latest version can be downloaded from here: http://www.dm.origin.com/mac/download

Additional advice on how to download games (thank you Tremayne for this tip):
When downloading from Origin, do NOT use the first install icon. Move your cursor over the game cover and click on the information (letter i) and then click on the install button from there. For some reason, downloads from Origin frequently become corrupted. Using the i reduces the chance of your download being corrupted. If you have already been unfortunate and have a corrupted download, then it is important to remove all traces of this before trying again, by doing a thorough, clean uninstallation first.

Are you running anti-virus software or any clean-up applications? If so, disable these, as they might be deleting files that Origin needs. A fast, stable internet connection will also help you.