The problem is that [...] after \\ is read as an optional argument. It can be used to specify more vertical space between the lines via e.g. \\[12pt]. But here you do not want your text [...] read as an argument to the \\ command, instead you need to tell LaTeX to take it easy with \\\relax:
\documentclass{report}
\begin{document}
\texttt{
[some text]\\
some other text\\\relax
[replace]\\
blablabla\\
}
\end{document}
In genaral you should not be using \\ to break lines on ordinary text. A blank line will give a new paragraph. \\ is appropriate in environments such as center or flushleft. For code examples the verbatim environment would be a better start:
\begin{verbatim}
[some text]
some other text
[replace]
blablabla
\end{verbatim}
Here the line breaks in your source are respected and you don't need \\. More sophisticated code typesetting is provided by packages such as listings.
\documentclass{report} \begin{document} \texttt{ [some text]\ some other text\\~ [replace]\ blablabla\ } \end{document}– bersanri Jun 27 '13 at 13:26