superscript numbers have disappeared

Well, I am a very inexperienced InDesign user. I am laying out a journal and all of the paragraph styles have already been created years ago. So, when I place text from a Word doc, I apply the appropriate paragraph style to the text. Then I copy and paste a superscript number from a previously existing layout into the new one, because sometimes the superscript numbers in the Word doc disappear when I place it into InDesign.

On my current layout, all of the superscript numbers made it over from the Word doc to the InDesign layout. And then lo and behold, one day I opened the InDesign files and all of the superscript numbers had disappeared from three of the articles in the layout--but remained in ONE article! It makes no sense.

I have no idea what a character style is or how to apply it so that my superscript numbers don't disappear.

Of course, this would all be easier if the function to place endnotes worked. I have tried many times, and InDesign won't place my endnotes from my Word docs. I have to add the endnotes in by copying and pasting from the Word doc into InDesign. If the endnotes were placed in InDesign as they are supposed to, then my superscript numbers would be connected to the endnotes and I'm guessing I wouldn't have to manually insert superscript numbers in the running text of the articles in InDesign when they sometimes don't make it over during "Place", or simply just disappear as they did in my current layout, after previously having been there.

Thanks for any and all advice!