Menu disapear on admin System/Configuration - Joomla! Forum - community, help and support

hi !
i have bug on backoffice, menu disapear when go system/configuration, can't activate modifications on it.

i have found problem jquery script (find chrome dev tools or firefox inspector consoles) :

index.php?option=com_config:177 uncaught referenceerror: jquery not defined
@ index.php?option=com_config:177
index.php failed load resource: server responded status of 500 (internal server error)

when go source code of page, can see loaded script don't know why there jquery code :

code: select all

<div class="modal hide fade" id="imagemodal_jform_offline_image">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal">×</button>
<h3>changer d'image</h3>
</div>
<div id="imagemodal_jform_offline_image-container">
</div>
</div>
<script>
jquery('#imagemodal_jform_offline_image').on('show ', function() {
document.getelementbyid('imagemodal_jform_offline_ image-container').innerhtml = '<div class="modal-body"><iframe class="iframe" src="" height="" width=""></ifram
e></div>';
});
</script>
<div class="input-prepend input-append">
<span rel="popover" class="add-on pop-helper field-media-preview" title="image sélectionnée" data-content="aucune image sélectionnée." data-original-title="image sélectionnée" data-trigger="hover">
<span class="icon-eye" aria-hidden="true"></span>
</span>
<input type="text" name="jform[offline_image]" id="jform_offline_image" value="" readonly="readonly" class="input-small hastooltip field-media-input input-large wf-media-input" />
<a class="btn add-on button-select">sélectionner</a>
<a class="btn icon-remove hastooltip add-on button-clear" title="effacer"></a>
</div>

the jquery script seems to in add offline image (the button doesent work anymore)

the code #imagemodal_jform_offline_image doesn't exist in files on server (i have scan of it)

so bug , how can fix ?

thanks lot helping

same problem here disappearing menu in global configuration , in modules.