KendraKat Isla Paradiso is the most broken of the EA worlds, and it's not close. The problems aren't the kind that cause save corruption, exactly, but problems can pile up to the point where the save is basically unplayable. It's why people always recommend playing in a fixed version of IP, or fixing the world manually, rather than using the default version.
For now, try loading your save with only NRaas mods, if you use them, nothing from any other source. If the save won't load, try the backup. Inside Documents > Electronic Arts > The Sims 3 > Saves, you'll see a folder with the save's name and another folder with the same name plus a .backup extension, for example IslaParadiso.sims3 and IslaParadiso.sims3.backup. Change the name and delete the .backup (e.g. IslaParadiso1.sims3), and the save should be available to select at the Main Menu.
Long term, these are the mods I and many others suggest for the overall health of your saves:
Sims 3 - Common Game Fixing Mods - Hero Approved | EA Forums - 8291748
Aside from that, running a MasterController town reset (NRaas > MC > Town Options > Reset Everything) every six to eight sim-weeks is helpful, and in some worlds it should be done more often, especially if you're noticing performance dragging somewhat. You can exclude the active lot under MC's Settings if you don't want your own sims reset.
There's no way to completely prevent save corruption, unfortunately. But what you can do is keep backups of your main save, a few at any given time, so that you can revert if and when you run into problems.
If you'd like help fixing up IP, let me know, whether it's in your current save (if it loads) or in a new one.
