Man has two guesses to unlock bitcoin worth $240m

Now, Thomas' Bitcoin portfolio is valued at a hefty US$233.6 million (AU$303.7 million), which would ordinarily be cause for celebration... if it weren't for the fact he somehow managed to lose the IronKey password.

Imagine having unfathomable wealth at your fingertips, around RM1 billion worth of assets-but not being able to access it because you forgot a simple password.

Thomas was given 7,002 Bitcoins more than 10 years ago for making a video how cryptocurrency works.

Alex Stamos, an internet security expert at Stanford Internet Observatory, said he believed he could crack the password within six months - in exchange for a 10 per cent cut of the digital fortune.

Thomas is not alone in being locked out from his Bitcoin fortune, as there is now $140 billion worth of Bitcoin that is either lost or left in wallets that can not be accessed, according to cyrptocurrency-data company Chainanalysis.

Since then he's tried to have a stab at guessing his password eight times, but none of these attempts have been successful.

Perhaps unsurprisingly, the dilemma has put him off cryptocurrencies.

"I would just lay in bed and think about it", Thomas told the New York Times.

The IronKey allows users 10 guesses before it encrypts its contents forever.

Currently, about $140bn worth of Bitcoin is lost or left in wallets that can not be accessed, according to cryptocurrency-data company Chainanalysis. "The reason we have banks is that we don't want to deal with all those things that banks do".

But Stefan Thomas and his forgotten password aren't exactly the first tragedy on the Bitcoin front.

And businesses helping retrieve digital currency receive multiple requests each day.

Thomas reportedly put the tokens into a wallet and stashed the lot, including access to his private keys, on a small hard drive device called an IronKey.

At the time worth more than £4m, this would now be valued at more than £250m. He accidentally threw away the hard disk that contained the bitcoin private keys.