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I’ve been using SketchUp for about half a year now. I’m experienced enough to know the basic tools.
The zoom selection worked to SEE the model but when i zoom out&orbit or just orbit it goes back to its grey background again
I found the model by using Outliner as gsharp suggested. I right clicked on the group and chose Zoom Selection. Then I select it along with the loose geometry and moved it all closer to the origin. With it all still selected, I copied it and pasted it in place in a new file. I expect you have some text label that is located at a long distance from the origin. There is a bug that occasionally pops up. It’s usually easier to just copy the model to a new file.
FWIW, make sure you keep your model close to the origin.
Your model has 11 leader texts that have lost their connection to reality, almost surely due to the bug that @DaveR mentioned. One known trigger for this bug is to delete the entity that a text is attached to. Until this bug is fixed (hopefully in SU 2019), the only safe process is to wait until the model is stable before attaching leader texts as annotation.
Alas, Trimble has almost never released a bug fix mid-year, especially if there is a way to avoid triggering the bug. Since I don’t work for them I can’t offer an explanation or excuse, but that’s how it has always been. For this particular bug there is a repeatable test case, lack of which is the most common reason a bug doesn’t get fixed. So, keep fingers crossed for SU 2019.