Currently, there is no WannaCry decryption tool or any other solution available, so users are strongly advised to follow prevention measures in order to protect themselves.
Keep your system Up-to-date: First of all, if you are using supported, but older versions of Windows operating system, keep your system up to date, or simply upgrade your system to Windows 10.
Using Unsupported Windows OS? If you are using unsupported versions of Windows, including Windows XP, Vista, Server 2003 or 2008, apply the emergency patch released by Microsoft today.
Enable Firewall: Enable firewall, and if it is already there, modify your firewall configurations to block access to SMB ports over the network or the Internet. The protocol operates on TCP ports 137, 139, and 445, and over UDP ports 137 and 138.
Disable SMB: Follow steps described by Microsoft to disable Server Message Block (SMB).
Keep your Antivirus software up-to-date: Virus definitions have already been updated to protect against this latest threat.
Backup Regularly: To always have a tight grip on all your important files and documents, keep a good backup routine in place that makes their copies to an external storage device that is not always connected to your PC.
Beware of Phishing: Always be suspicious of uninvited documents sent an email and never click on links inside those documents unless verifying the source.
Video Demo of WannaCry Ransomware Infection