im looking for the tool which takes the C# source code as input and does the processing based on the rules set like change all the method parameter to camel case or pascal case vice verse and gived output the modified source code.
take a look at resharper
it is not really meant for post-coding cleanup, so it might not be exactly what you need ..
but it helps you prevent having to do said clean-up by commenting on your coding as you are working
from the webiste:
ReSharper in a nutshell
ReSharper provides solution-wide error highlighting on the fly, instant solutions for found errors, over 30 advanced code refactorings, superior unit testing tools, handy navigation and search features, single-click code formatting and cleanup, automatic code generation and templates, and a lot more productivity features for C#, VB.NET, ASP.NET, XML, and XAML.
There is also StyleCop
StyleCop analyzes C# source code to enforce a set of style and consistency rules. It can be run from inside of Visual Studio or integrated into an MSBuild project