James Howells, an IT guy, lost 7,500 bitcoins in November 2013. While he was cleaning his desk at home, he threw away his hard disk containing the private keys of bitcoins which he had mined in 2010.
The realization dawned on him when he read news of a Norweigan man who made a fortune by buying BTC at a low price.
He searched and searched, but could not find his hard disk.
At present, the worth of 7,500 BTC is approximately $19.4 million.
Without the private key, the funds are lost forever no one can use them.
Until this point in time, it is estimated that around 25% of all bitcoins have been forever lost.