Unless you back up regularly and can afford to revert to an image prior to infection by keeping your private data off your hard drive. Then you revert and tell the SOBs to sit on it and spin.
Professionals backup to grandfather drives. Meaning, backups on different hard drives. Let's say your current daily backup saves to another drive and both are infected. If you regularly backup the backup drive weekly to a third drive, then that third drive is unaffected. At most you lose a week's worth of new data. It's always a good idea to periodically swap backup drives and store one away as a backup to the backup (store in a safe). Especially if your daily backup is near your work drive; accidents do happen that can take out both drives. Even better, store a backup drive off site in case of fire or theft.
That is why I still prefer to still have a tape backup somewhere. Doesn’t have to be every night anymore, but at least once a month or once a week and take it off-site. So many people are getting burned with using external drives as backups that get infected too along with the network drives.