I've installed the sims 3 onto my computer again as I love the game and I had it uninstalled due to a lot of bad cc, glitched saves, non -working expansions etc. But when I re-installed the game (through disc 100% legit) the games laucher just keeps crashing and saying debugging. And if I bypass the laucher the game wont open at all. It opens a blank screen for a second and then closes itself. I've re-installed the game 3 times and it still wont work. Do I need to download it through origin? or get it in a non-legit way? I mean I have bought it so it cant be wrong. Please help if you can. <3

The Disc's should still work if they are unscratched and if you didn't get any error messages while installing those. Is this the same PC when you had Sims 3 installed?

If, so I would uninstall again and check the Program Files - folder (Program Files (x86)\Electronics Arts\ The Sims 3\) + Documents - folder (Documents\Electronics Arts\The Sims 3) on a OS WIN, to see if there are any old traces left in your PC of the Sims 3 that you manually added in the past. Then I would check the registry if the uninstaller has also wiped out any traces in there.

On this link under "Cleaning up Leftover Folders" and "Cleaning up the Registry", you can find more details on this method.

Once you are sure there are no traces of the Sims 3 lingering/hiding somewhere, then start reinstalling the Base Game first and check if it will run solely, after that reinstall you other EP's / SP's.