The Sims 3 game won't start up anymore when the mods folder is in it

Fratsje​  Do you use NRaas ErrorTrap?  If so, please download a fresh copy.  The Sims 3 update of almost a year ago changed the game's internal build number, which meant core mods like ET needed to be updated as well.  (Most mods are script or tuning mods, which were unaffected.)

If that doesn't help, create a new Mods Framework and add a fresh download of one NRaas mod, delete scriptCache.package again, then see whether the game works.  I'm not saying you have to delete all your other mods and custom content, only that this is a useful test.