citet and citep behaves like cite

The author-year citation style requires usage of BibTeX or specially formatted \bibitem commands.

If you don't want to use BibTeX, then you must hand format your thebibliography environment as in the following example.

\documentclass[11pt]{article}


\usepackage[sort&compress,square,comma,authoryear]{natbib}

% makes color citations
\usepackage[colorlinks=true,urlcolor=blue,citecolor=red,linkcolor=red,bookmarks=true]{hyperref}

% document begin
\begin{document}

% author and title
\title{My Article}
\author{Author Name}
\date{Today}
\maketitle

Blablabla said by \cite{lamport94} cite example. Blablabla said by \cite[p.~215]{impj} cite example. Blablabla said by \cite{fo,norman,lamport94} multiple cite example. Blablabla said by \nocite{lamport94} nocite example.
Blablabla said by \citep{lamport94} citep example. Blablabla said by \citet*{impj} citet example. Blablabla said by \citet{impj} citet example.

% this must be set to use natbib (citep, citet) but requires BibTeX
\bibliographystyle{plainnat}

% number 99 determines how much citation can be included in file (maximum 99)
\begin{thebibliography}{99}

\bibitem[Lamport(1994)]{lamport94}
  Leslie Lamport,
  \emph{\LaTeX: A Document Preparation System}.
  Addison Wesley, Massachusetts,
  2nd Edition,
  1994.

\bibitem[Dower(1991)]{notes} John W. Dower {\em Readings compiled for History
  21.479.}  1991.

\bibitem[Japan Reader(1973)]{impj}  The Japan Reader {\em Imperial Japan 1800-1945} 1973:
  Random House, N.Y.

\bibitem[Norman(1940)]{norman} E. H. Norman {\em Japan's emergence as a modern
  state} 1940: International Secretariat, Institute of Pacific
  Relations.

\bibitem[Wakabayashi(1986]{fo} Bob Tadashi Wakabayashi {\em Anti-Foreignism and Western
  Learning in Early-Modern Japan} 1986: Harvard University Press.

\end{thebibliography}



\end{document}

Never pass explicit driver names to hyperref.

---

If you want a "mixed" system like "Author [number]", then you can say

\usepackage[sort&compress,square,comma,numbers]{natbib}

\DeclareRobustCommand{\citeext}[1]{\citeauthor{#1}~\cite{#1}}

and then \citeext{lamport} will give you

Lamport [1]