Currently there is no way to decrypt files encrypted by Locky and your best way to recover is from your backups.

How does Locky get onto the PC

Locky is currently being distributed via an email that has an attachment with malicious macro inside the word attachment. The email will have a subject ATTN: Invoice J98223146 or similar and asks you to pay the attached invoice. Naturally end users click on the link to see what the invoice is for and then become infected with the virus and the encryption begins.