I was using the Allegro PCB Editor(OrCAD 16.0). In that all components are in same side.So only i had asked that doubt to change the component top to bottom.
This Option is been not enabled in my Edit -> Move and then click the RMB and mirror the component.
What is RMB ?
Send the details clearly.
RMB = Right Mouse Button
There are several ways to change sides (mirror) in Allegro.
1) Edit->Mirror, then click on the part
2) Edit->Move, click on the part, then RMB, mirror
3) Place->Manually, click on the part, RMB mirror
Hope that helps!