Ransomeware is a type of malware in which hackers lock you out of your data until you pay the hackers a fee.
Security professionals may be able to retrieve your data without you having to pay the ransom.
However, the latest generation of ransomware actually encrypts your data. Then, if you pay the ransom the hackers will provide you with the decryption key so that you can decrypt and retrieve your data.
To help ensure protection against or recovery from ransomeware, make sure continually run malware scans and keep an offline backup of your data.