It is not uncommon to lose data due to external virus attack or due to some hardware failure.
All establishments who handle important data must always have an Automatic System of Recovery in place to handle any emergency situations or data loss.
It basically involves making a mirror copy of your disk.
Whenever you save any information on the hard disk it gets stored at two places, two different physical hard drives.
Those two drives can reside on the same system or on different physical locations.
They are interconnected with each through network.
If you have a setup like that you need not to worry about any data loss.
Big companies keep simultaneous copies of their data in several places on different physical locations.
You can also use internet for taking hot and cold backups of your system.
As far as two systems are in network you can maintain a regular mirror copy of the hard disk.
Automatic system recovery (ASM), continuously save the state of source system and keep the backup computer always up to date.
So that in case of any emergency you can simply replace the system and your work is not at all affected due to failures, damages or accidents.
Only authorized technical people should be allowed access to the recovery system.
Manage its security tightly by frequently changing passwords.
Your system should be designed such a way that you should able to recover data within minutes and with minimum effort.
There are some readymade software solutions available that can restore your system to the point specified with just one simple click.
While continuing with your work you should also have a facility to investigate the exact problem that actually caused the damage and resulted in data loss.
With this you can control that factor and avoid similar situations in future.