He said: 'The company that hosts the email account which the ransomware asks you to contact has closed the account.
There's no way to get files back.'It's early days - we don't know if we can find a fix yet.
Hackers have unleashed a major cyber attack causing huge disruption to companies and governments across the globe including in the UK, US and Russia.
The Petya ransomware hijacks victims' computers before encrypting their files and holding them hostage until a fee is paid.
One security researcher going by the name Bleeping Computer told Mail Online that x-ray machines and other critical medical devices could be deactivated in hospitals, adding: 'We're going to see wide-scale damage.'He continued: 'The biggest computers that may have an issue are those running old legacy hardware or software systems such as healthcare and control systems for industrial services.
Things like that that are running on archaic operating systems simply because they don't have the ability to upgrade.'There was a power plant infected by this which is really scary because those are the most vulnerable types of systems.'Russia's Rosneft oil company and steel firm Evraz, Danish shipping giant A. Moller-Maersk, and global law firm DLA Piper confirmed issues, along with French industrial group Saint-Gobain.
'It's like somebody sneezing into a train full of people,' said Botezatu.
The screen also warns not to turn the computer off otherwise all data will be lost.
But if it's decryptable we will find a way.'Hutchins, 22, continued: 'Everyone's looking at this right now and I'm working with other researchers.
'I was just praying it wasn't the Wannacry exploit again.
He called the attack 'unprecedented', though said vital services would not be affected.
Another screen with red text warns that files on the computer have been encrypted and will only be released if a payment of £300 in anonymous online currency Bitcoin is made.