Once compiled, its no longer Bmax code. It uses a c compiler to compile, so everything ends up as any other c code would and there is no direct way to get it back. It would be a lot of would I would think to decompile, analyze and then convert to Bmax syntax. This is the reason you can use c code directly within Bmax should you choose to do so.
So all in all probably not something anyone is willing to attempt. You really should try and implement a good backup plan using cd,dvd,usbsticks,usbhdd,etc.. Not that it helps you now with your current problem, but to prevent similar problems in future. I have an automated software running which syncronize my code folders to external hdd which has two disc where the files are duplicated. This ensures me to have my code on three seperate hdd, which should be secure enough, at least I hope.
