If your pictures, videos and documents are encrypted and a “Your personal files are encrypted” alert is asking for money (usually in Bitcoins) to recover the files, then your computer has been infected with a file-encrypting ransomware.
These file-encrypting ransomware programs are malware, which will encrypt the personal documents found on victim’s computer using RSA-2048 key (AES CBC 256-bit encryption algorithm). Then displays a message which offers to decrypt the data if a payment (with Bitcoins) is made within 96 hours, otherwise the data will be destroyed.
The most known ransomware programs that use the “Your personal files are encrypted” message are: Wana Decrypt0r 2.0, CryptoLocker, Crypt0l0cker, Alpha Crypt, TeslaCrypt, CoinVault, Bit Crypt, CTB-Locker or TorrentLocker.