I'm using book style, but it happens with a report style, too. I'm using the \chapter* command and I want that the chapter section appears in the table of contents, but it doesn't appear. This is the code:
\documentclass[14pt,a4paper,twoside,spanish,openany]{book}
\usepackage[spanish,activeacute]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{amssymb,amsmath,amsthm, mathtools}
\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\usepackage{fancyhdr}
\renewcommand{\baselinestretch }{1.3}
\renewcommand{\thesection}{\arabic{section}}
\newtheorem{theorem}{Teorema}[section]
\newtheorem{lemma}{Lema}[section]
\newtheorem{proposition}{Proposición}[section]
\newtheorem{corollary}{Corolario}[section]
\theoremstyle{definition}
\newtheorem{definition}{Definición}[section]
\theoremstyle{example}
\newtheorem{example}{Ejemplo}[section]
\theoremstyle{remark}
\newtheorem{remark}{Nota}
\pagestyle{fancy}
\lhead{TEMA 3}
\rhead{\thepage }
\chead{Combinatoria}
\rfoot{Oposiciones}
\rhead{\thepage }
\renewcommand{\footrulewidth}{0.4pt}
\renewcommand{\headrulewidth}{0.4pt}
\begin{document}
\author{Cristobal López Silla}
\title{Tema 3 - Técnicas De Recuento.Combinatoria.}
\date{}
\tableofcontents
\pagebreak
\chapter*{TEMA 3.\\Técnicas De Recuento.Combinatoria.}
\section{Introducción A Las Técnicas De Recuento.}
\end{document}
Thanks

\chapter*{...} \addcontentsline{toc}{chapter}{...}. But be careful not to insert stuff like\\, since that wouldn't make sense. – Werner Oct 08 '14 at 16:21