Decompile AssemblyCSharp.dll Into CSharp Files

On previous night I made apk (development mode) just to try my game and it work fine. Today while
further developing game, due to a sudden electric cut my one CSharp damage , when I try to open it via Notepad++ it show:
[null][null][null][null][null][null][null][null]

Please can anyone suggest me any way to decompile Assemble-CSharp.dll from apk. Writing whole CSharp file is a headache for me because its a big file. Please suggest me a way to do that.

Finally I figured it out. I just use .NET reflector to decompile .Net assembly of Assembly-CSharp.dll


Some problem are also linked with this. You must need to check these decompiled codes manually because they contains many unfamiliar statements.