And when installing the new OS, he should make sure to get a legal and licensed one from a direct dealer or straight from the company. There are a lot of pirated OS speculating on the software market, and most of them have this virus's design to only target crypto users.

Firstly sorry for your loss, hopefully you will recover from it.

The next thing is to look for solution to avoid future occurrence, i am a bit confused about your story is it that the transaction was done directly from your device (physical attack) or a through phishing attack or something like s malware on your device. If it is physical attack then you to be extra cautious of who get close to devices that holds your coin.

If it is malware I think you might need to total format your device as the malware would still be on it. If best look towards cold storage. If it is phishing attack then you need to take correction of sites you visit with such devices. Cold storage remains the best solution