It's too late to restore the code. Like it or not, writing the code again can be still easier then decompilation.
You should rather forget about the lost code and concentrate of the future efforts. And, for the immediate future, you should realize: right now, you are not really developing code and care about your valuable code asserts, because you are not using
Revision Control Systems,
http://en.wikipedia.org/wiki/Revision_Control_System[
^].
You should start using one immediately, not tomorrow, but today. It can be open-source and free, well maintained, extremely lightweight and, most importantly, extremely dependable. Please see this discussion:
Revision control systems, which to choose from?[
^].
For some more information on some particular systems, please see my past answers:
Needs some words of wisedom to set up and/or use a server[
^],
Make an unclickable form[
^],
How can i structured to arrange source code when i create a new solution[
^],
Reviews at Apache Subversion[
^].
—SA