ASP.NET code missing problem

Question

Good morning

 

As I developed an asp.net web site that contains classlibrary using C#.

due to some hardware problem I had to change my machine and I copied my project folder and managed on another machine.But here I am getting only .dll file not .cs files from classlibrary class files. so that I can edit code.

Sir, is there any way to solve this problem please tell me.I am searching for it on google but can not get satisfactory reply.