is it no longer showing in the outliner? If not, then afraid it might be gone. Are you set up for incremental saves? If so, you might be able to open from a point before it disappeared.
I've had geometry disappear on me also, but undo immediately and that seems to bring it back for me.
AIM: mhcannonDMC
"If you love your job, you'll never work another day in your life."