I WANT TO PERFORM THE UNDO IN STAR-CD ,PLEASE HELP ME

REGARDS

There is no "undo" in STAR-CD. There is "vundo" for vertex operations. If you are going to make a change to the model that you might not do correctly the first time, it's best to save the model first. Then if the result isn't what you were expecting, you can resume from the last save (File --> Resume). You can also use the "recover" command, which executes previous commands from the .echo file. Check the help on "reco." (On the command line: help reco)