horrible routing problem out nowhere

Could you possibly please tell what world you're having this problem in? Is it an EA world, or a user made world?
You can also upload screenshots to external hosting sites like photobucket, imgur, or image shack, and then put a link here. If you're not a full member it might not be a clickable link, but we can still paste it into our browsers and see what's going on. Screenshots would be helpful...
Though, @Igazor seems to be fairly good at discerning problems without pics, so hopefully he might be along in a little while to try and help.

The black balls you are seeing are unwanted, usually invisible and non-selectable objects that can indeed block routing. A common example would be abandoned social jigs, but that's a lot of those to be seeing at once. Resetting will not flush them out.

On one such infested lot, click on the ground and use MasterController to help identify them further and get rid of them.
NRaas > MC > Object Stats > Non-Inventory (MC Cheats add-on module required)

Do you see anything showing up in the list of all non-inventory objects that looks like these black balls? If so, what are they? If they have the name "jig" in them of any kind, select them to flush all at once. Be very careful not to flush something really important, like your actual sims or their plumbobs.

If you repeat the above by clicking on the ground of the World Lot (that is, a place that isn't really on any other lot such as a road or sidewalk), you should be able to use Non-Inventory, Local or Global, one of those, after a long pause to get a very long list of all objects in your world and flush the rest of them all at once.

The white cube that @ARRensch mentions is something different. That would indicate an EA store item that is not loading correctly at the time it is needed or perhaps got uninstalled and the game cannot find a reasonable substitute.

MasterController Cheats is one of several optional add-on modules for MasterController. "MC" is just an abbreviation. The module adds more commands to the ones that come with MasterController base. You must have the module to use the commands I described; make sure the versions match/are compatible with your game's patch level.
http://nraas.wikispaces.com/MasterController

"DivinylsFan;13984329" wrote:
I would go to Town Edit, save a copy of your favourite household/s to library and then start a new game in a new world, and put your saved household/s into that. Because it looks like it's way too much hassle to fix that .. mod this cheat that do this do that .. sometimes it's easier to let it go

Except in this case the player already had MasterController in place and was only missing an add-on extension for the cleanup task. The issue for them was actually caused by a different mod that was not updated to work with or beyond the Pets EP, so had they just moved everyone to another world with their pets the problem would have started building up again almost immediately.

We get that not everyone wants to use mods to fix issues in their games. But for those who already are (as in this case) or those who wish to try, the support is there if they seek it out.

"Sindocat;13986606" wrote:
Not to stray off topic, @igazor, but speaking as someone who has generally tried to avoid mods, this attitude and approach makes me much more confident of NRass products. Thanks for being here on the scene to help. :)

I think my colleagues and I have learned more about how this game operates by supporting other users than we have by actually playing it ourselves (slight exaggeration). Wish more would come to our site for support when needed as that's kind of what we are there for, but ah well can't have everything.

And thanks for the kind words. :)

hii ty the reply :)

my world is the pet expansion one Appaloosa Plains

it has work all fine and suddenly everyone stuck can not even pass stairs or goes arround the localbar (door is front but sim goes to back side to cry on a wall he can not get inside)
same one i ask to swim together my sim goes to the pool the one i ask to join can not find the way

more and more those issues and here on screenshot

ttp://postimg.org/image/r4plrvlz5/

im not allowed to post links it say
You have to be around for a little while longer before you can post links

ssoo the link is above "ttp" just change into http :)

i can not understand this blue crystal they crying about but this appear by every route fail

You may have to go into Edit Town and evict your family, then move them back in (and if you go into testingcheatsenabled freerealestate, you won't have to pay for your house again).

hmm but this is happen in every household including community
as the screenshot there is on a friends party home all those living sims there on the picture are complainning about no route those are not my family but the same story happen at my home too

http://s24.postimg.org/img5njfgk/Screenshot_40.jpg

Here, I posted it for you, thanks for uploading it :)
I... don't think I've ever seen a town in its entirety have complete and utter route fail like you're describing. Do you use mods at all? Like the NRASS suit of mods?
I think that blue crystal thing is some kind of pet bed or blanket, though I don't see why it would be affecting the entire town.

You could try resetting them all maybe?
Here's the cheat: http://www.carls-sims-4-guide.com/forum/index.php?topic=451.0

You'd probably want to reset everybody, which is the cheat found at the bottom of the post. Whether this will fix it or they all get stuck again... I don't know.