SharePoint - .dll file

hi,
I have .wsp file which i have received in which i have  dll file and some xml files..can you please suggest how can i modify .dll file to make some changes in there without having source code ..Please reply as soon as possible..

You can decompile the dll assembly with Reflector. There is also a Reflector add-in called FileDisassembler which will save all the decompiled class files along with a project file to match.

as reflector is no longer free ( shame on redgate! )

there is an opensource one developed by the nice eople at sharpdevlop

here http://wiki.sharpdevelop.net/ILSpy.ashx

not quite as polished as reflector, but will do what you need

this does of course assume that the dll is .net and not c++ or the like

You need the source code and a compiler suite for that. Most popular here is MS Visual Studio for modifying a DLL or you need to write your own source code for creating a new one.

PE viewers can allow you to debug a few aspects of such DLLs, but you can't change their behaviors with them... you could do that with a hex editor, if you have nothing planning for the rest of your life.

The only working way is getting the source code and essentially change the blueprints to produce a new DLL every time. That is how compilers work.

Hope this will help you.