Model save is now a very small file that bug splats

built large file this weekend, saved it, came back this am to open and it splats, looking at file in explorer it is a very small file 1233kb where as older files that do open are min 26623 kb
I’ve lost this twice do I have a setting wrong somehow in sketch up?

Hard to say without more information. How about sharing your .skp file?

What extensions do you have installed?

What is the graphics card?

Your profile says your operating system is dos. Presumably you mean Windows. Which version of Windows?

When you installed SketchUp did you install it correctly? That involves right clicking on the downloaded installer and choosing Run as administrator.