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The reason why you can't see the operationmenu for the XOOPS default template set is because this template set is readonly for safety reasons.
You'll have to clone the default template set or upload a new set to modify it. I don't know why you cannot see your chinamu templates anymore. You can try updating your modules in the module admin section.
Otherwise you must have done something wrong. Did you click on the delete link
?
I hope you have a backup....