I lost my margins, header and footer and page numbers, don’t know how to get them back.
Read these guidelines and edit (the link below your question with a slanted pencil) your question if you really intend to get relevant suggestions. Be aware we are not behind your shoulder watching your screen.
I assume you are storing your document as a .odt file not a ,doc or .docx. If so, this information is stored on the Page Style. See HELP PAGE STYLES for a range of help. Here you can set margins, headers. footers, insert page numbers. The question is, how did you lose these settings to start with. Did someone else give you the document?