You can reset individual toolbars to the factory defaults by right-clicking the empty part of them and selecting the menu option to do so.
If you don't want to lose other changes to the toolbar, it could be duplicated first (so you have your own differently named copy of the Operations toolbar, and then reset the main Operations toolbar).
Or you can paste this to your toolbar which will re-create the Help menu:
<?xml version="1.0"?><?xml version="1.0"?>
<button backcol="none" display="both" label_pos="left" textcol="none" type="menu">
<label>&Help</label>
<icon1>#help</icon1>
<button backcol="none" display="both" hotkey="f1" label_pos="right" textcol="none">
<label>&Help\tF1</label>
<tip>Displays the Directory Opus online help</tip>
<icon1>#help</icon1>
<function type="normal">
<instruction>Help</instruction>
</function>
</button>
<button backcol="none" display="both" label_pos="right" textcol="none">
<label>&Keyboard Map...</label>
<tip>View and edit custom hotkeys</tip>
<icon1>#keyboardmap</icon1>
<function type="normal">
<instruction>Prefs KEYS</instruction>
</function>
</button>
<button backcol="none" display="both" label_pos="right" separate="yes" textcol="none" type="menu">
<label>&Logs</label>
<icon1>#logs</icon1>
<button backcol="none" display="label" label_pos="right" textcol="none">
<label>&FTP Logs</label>
<tip>Displays the logs of FTP activity</tip>
<function type="normal">
<instruction>Set UTILITY=FTPLog,Toggle</instruction>
</function>
</button>
<button backcol="none" display="label" label_pos="right" textcol="none">
<label>F&ile Log</label>
<tip>Displays a log of file and folder operations</tip>
<function type="normal">
<instruction>Set UTILITY=FileLog,Toggle</instruction>
</function>
</button>
<button backcol="none" display="label" label_pos="right" textcol="none">
<label>&Undo Log</label>
<tip>Undo the previous file action (copy, delete, rename, move, etc)</tip>
<function type="normal">
<instruction>Set UTILITY=Undo,Toggle</instruction>
</function>
</button>
<button backcol="none" display="label" label_pos="right" textcol="none">
<label>&Email Log</label>
<tip>Displays a log of sent and pending emails</tip>
<function type="normal">
<instruction>Set UTILITY=Email,Toggle</instruction>
</function>
</button>
<button backcol="none" display="label" label_pos="right" textcol="none">
<label>&Other Logs</label>
<tip>Displays logs for other activities such as Scripts</tip>
<function type="normal">
<instruction>Set UTILITY=OtherLog,Toggle</instruction>
</function>
</button>
</button>
<button backcol="none" display="both" label_pos="right" textcol="none" type="menu">
<label>&Directory Opus on the Web</label>
<icon1>#ftpconnect</icon1>
<button backcol="none" display="label" label_pos="right" textcol="none">
<label>&Directory Opus Home</label>
<tip>Access the main GP Software web site</tip>
<function type="normal">
<instruction>http://www.gpsoft.com.au/DScripts/redirect.asp?page=home</instruction>
</function>
</button>
<button backcol="none" display="label" label_pos="right" separate="yes" textcol="none">
<label>&Resource Centre</label>
<tip>Directory Opus User Resource Centre</tip>
<function type="normal">
<instruction>http://www.gpsoft.com.au/DScripts/redirect.asp?page=resource</instruction>
</function>
</button>
<button backcol="none" display="label" label_pos="right" textcol="none">
<label>&Product News</label>
<tip>Access the latest Directory Opus news</tip>
<function type="normal">
<instruction>http://www.gpsoft.com.au/DScripts/redirect.asp?page=news</instruction>
</function>
</button>
<button backcol="none" display="label" label_pos="right" textcol="none">
<label>&Frequently Asked Questions</label>
<tip>Search our database of Frequently Asked Questions</tip>
<function type="normal">
<instruction>http://www.gpsoft.com.au/DScripts/redirect.asp?page=faq</instruction>
</function>
</button>
<button backcol="none" display="label" label_pos="right" separate="yes" textcol="none">
<label>&Online Support</label>
<tip>Online Directory Opus support page</tip>
<function type="normal">
<instruction>http://www.gpsoft.com.au/DScripts/redirect.asp?page=support</instruction>
</function>
</button>
<button backcol="none" display="label" label_pos="right" textcol="none">
<label>&Getting to know Directory Opus</label>
<tip>An excellent online tutorial to introduce you to Directory Opus</tip>
<function type="normal">
<instruction>http://www.gpsoft.com.au/DScripts/redirect.asp?page=intro</instruction>
</function>
</button>
</button>
<button backcol="none" display="both" label_pos="right" separate="yes" textcol="none">
<label>&Check For Program Updates...</label>
<tip>Check for updated versions of Directory Opus</tip>
<icon1>#checkforupdates</icon1>
<function type="normal">
<instruction>Help CHECKUPDATE</instruction>
</function>
</button>
<button backcol="none" display="both" label_pos="right" textcol="none">
<label>L&icence Manager...</label>
<tip>Displays the Directory Opus Licence Manager</tip>
<icon1>#licencemanager</icon1>
<function type="normal">
<instruction>Help LICENCEMANAGER</instruction>
</function>
</button>
<button backcol="none" display="both" label_pos="right" separate="yes" textcol="none">
<label>&About Directory Opus...</label>
<tip>Displays Directory Opus copyright and version information</tip>
<icon1>#about</icon1>
<function type="normal">
<instruction>Help ABOUT</instruction>
</function>
</button>
<button backcol="none" display="label" label_pos="right" textcol="none">
<label>H&elp Menu Marker</label>
<tip>Marks the place in a menu where Namespace-specific menu items from the 'Help' menu are to be displayed</tip>
<function type="normal">
<instruction>Marker MENU=Help</instruction>
</function>
</button>
</button>