Hello,
You can try creating a new project (with the same parameters and heightmap) and gradually import all the template libraries from the old project.
Once that's done,you should close Terrain Builder and then add the object layers from the old project to the new one as well, and try loading the new project.

Hello Geez,

Seems good, It can be a nice option to import everythink on another one project recently created adding the layers and continue from that.

But how can I import terrain terraforming, because I do a lot on the map. And if I add every object at copy non terraformed map it should put everything under the ground.

Thank you very much for trying to help !
It is a huge project so any kind of help is a good pleasure and wellcome.

If by "terraforming" you means the heightmap - the terrain, in your old (broken) project it will be one of the *.v4d files, but we don’t know exactly which one to use, since it varies from project to project.