Avast Decryption Tool for Bart unlocks your PC from Bart, ransomware that changes your wallpaper to a ransomware message. All the Avast Decryption Tools are available in one zip here.
Bart adds .bart.zip to the end of filenames. These are encrypted ZIP archives containing the original files.
After encrypting your files, Bart changes your desktop wallpaper to an image like the one below. The text on this image can also be used to help identify Bart and is stored on the desktop in files named recover.bmp and recover.txt.