Change one of your non-3D viewport windows to Outliner. Do you see it in the list? Make sure it is not hidden, the eyeball will be closed in the Outliner if it is. Move your mouse into the 3D viewport and press the tilda ‘~’ key. This will select all layers, perhaps it was moved to a non-visible layer. Also, if you have the name selected in the Outliner move your mouse into the 3D viewport and press the num-pad period key. This will cause the 3D viewport to auto-locate your object and center it ion the screen. Also try the Home key as well.