I am using \tableofcontents in my report sty file. The problem is that my content is so lengthy and it's second line is starting immediate under the chapter number. but it should not be like that... what should i do???

Too long for a comment.

I cannot reproduce it, the second and further lines of the chapter title are aligned with the start of the title text in the first line and do not start immediately below the chapter number:

\documentclass{report}
\usepackage{lipsum}

\begin{document}
\tableofcontents
\chapter[{\protect\lipsum*[2]}]{Second lipsum paragraph}
\section{Section title}
\end{document}


In the example I have used the optional argument of \chapter to provide a very long chapter title for the table of contents. You could do the opposite and provide a shorter version of the chapter title to avoid a second line.

Otherwise provide a minimal working example (MWE) that shows the problem.