If you don't see your Orca3D toolbars, follow the steps below to recover them.
In Rhino, open the Rhino options dialog (command "Options"). In this dialog, go to "Rhino Options"->"Toolbars" on the list on the left side of the dialog. In the list of files, do you see "Orca3D"?
If so, you may select the toolbars that you wish to be displayed from the list and click "OK".
If not, click the "File" button at the top of the dialog and choose "Open". This will bring up a file dialog box for you to find the Orca3D toolbar file. The folder containing the Orca3D toolbars is typically hidden on most computers, so instead of searching for it, copy and paste the following address into the address bar of the file dialog: