objects gone

[Llian]

after hours of working to put on the grids , stairs, etc..i'm not finding them missing from the drawings..what can possibly happen???

[Anonymous]

-Do you have the library loaded?
-Layers off?

[Llian]

the file was opened and all i did was to walk away and came back 15mins to see this disppeared!...

[Anonymous]

Are there any objects visible at all?
Are any regular elements (for instance walls) visible?
Do you refer to 2D or 3D?

[Llian]

just the grid and the stairs gone and now i have re-created them again...