Solids are disappeared from the model

I am a frequent user of rhino. Recently I am doing a high rise architecture project and hit a huge problem.The solid disappeared or shifted from the lines which I originally created. My friend also face the same problem with his own project at similar period. Is there a way to recover the model? Or is the model already crashed?

I have tried rendering the space which is appeared as there are no object there. However the selection showed as there is no problem with the extrusion. Thank you so much for any advice!!

Hi Venus - please try running the RefreshShade command on these objects - does that help at all?

-Pascal

Hi Pascal:
The command fixed all the affected objects! Thank you very much!!! It really helps a lot to me!! Thank you!