Sims won't age at all

@killmrpotato  This is, unfortunately, not all that uncommon a glitch.  Without mods, fixing it is hit or miss, as in, sometimes the interventions work, and sometimes they don't.  You've covered some of the usual troubleshooting steps, but maybe combining a few of them may help.  And it's a good idea to use "save as" to rename the save every time you try a new approach, so you'll have backups if you need them and can experiment freely without worrying about the consequences.

While testing, be sure to delete the five cache files in your Sims 3 game folder in Documents every time you quit.  They should be deleted regularly anyway, as they tend to fill up with stale data.  For reference, they are:

• CASPartCache.package
• compositorCache.package
• scriptCache.package
• simCompositorCache.package
• socialCache.package

The first thing to try is removing options.ini from your game folder.  You'll need to reset all of your game options, but it might help.  If it doesn't, delete options.ini again, then turn aging off.  Save as, quit, delete the cache files, load the save, turn aging on again, quit, delete the cache files, and reload to see whether it helped.  It might take a couple of sim-days to be sure, so you may want to save after the final reload and then just use ultra speed to get through the next few nights.

If this doesn't help, evict the sims, save their house to the bin, bulldoze the lot, and replace the sims.  The more thorough approach would be to turn aging off first, go through the eviction sequence, save, quit, turn aging back on, evict and replace again, quit, and reload.

Finally, you can try switching to a different household and then evicting your original sims, combined with toggling aging on and off.

The fact is though that this glitch can be stubborn, and there isn't always a way to fix it.