Gof, we can understand your English. No worry.
Well, there is something I want you to explain again. It's not possible to send 'all files' in C:\Windows to Chest.
Chest, by default, has a limit. Only infected files (not folders) will be sent there.
Second, sadly, it's not possible to recover a file from Chest if you can't boot to Windows.
If you can boot in Safe Mode, just run C:\Program Files\Alwil Softwarel\avast4\ashChest.exe and restore the file to the original place or extract it to an usb drive, for instance.
If you can only boot by DOS, you need to access the folder C:\Program Files\Alwil Softwarel\avast4\DATA\chest and copy all files from there. You'll have to 'add' them to another computer, clean, with avast, to the same folder. Open avast chest and you'll see the files again. Extract them and copy to the original computer.
But I'm not sure your friend needs this... can't he boot?