If ransomware is written well you won’t be able to decrypt the data or crack the encryption. If it is written with mistakes then it might be possible to decrypt the data. To determine if the data can be decrypted, google the name of the ransomware and see what the results tell you. Also, find out what happens when you pay the fine. Do they decrypt the data? Some don’t even decrypt your files if you pay. Options;
1. Restore data from backup and rebuild the system from the OS up. See volume 4 of The complete cyber security course for info on malware removal.
2. Try to decrypt the data if it’s possible. Google it. Then start doing backups!
3. Pay ransom. Then start doing backups!
4. Accept the loss of your data. Then start doing backups!