How do I run Fixup in the document?

I have a form with an embedded excel file. I don’t know what the user did but when we tried to open it again, it won’t and it has an error message “one or more of the source document’s missing. run fixup to delete the document in the source database”. How do i run fixup? Will this delete the document? If it will, is there any other way that can rescue the document?