Ransomware is malware that locks your computer or files...

Google for below tools:

WildFire Decryptor
Tool made by Intel Security & Tool made by Kaspersky La

Chimera Decryptor

Teslacrypt Decryptor

Shade Decryptor

CoinVault Decryptor

Rannoh Decryptor (updated 03-10-2016)

Rakhni Decryptor