CryptoLocker is a new sophisticated malware that is designed to attack Windows operating system by encrypting all the files from the system. To decrypt the mentioned files, user has to pay a ransom (usually 300 USD/EUR) or 2 BitCoins.
If your files have been encrypted by CryptoLocker, we recommend you to follow these steps:
1) Remove CryptoLocker virus from the computer. In some cases it is required to reinstall the computer.
2) Restore the files from a date prior to having the virus.
It is not known whether encrypted files are backed up or not. It depends on whether modification date of the files change when being altered by the virus. If modification date is not changed by the virus, then the infected files will not be backed up and you can simply restore the latest versions of your files.