This will be a very difficult case to solve, and some might not even want to give their two cents because they don’t see any possibility of you getting your coins back.
In 2011 I’ve bought 100+ BTC on some cryptocurrency stock exchange and now I can not remember what was the site exactly.
I’ve got only email which also was a login name and my passport information.
From what you have written it seems like you used a centralized exchange to buy your coin; but the issue here now is “are they still operating?” If you don’t remember the name of the exchange you used i think it’s because it was not a popular one and might have closed down their service and that’s one issue you’re more likely to face. And since it’s a centralized exchange there’s nothing you can do to reclaim your coins back if it my speculation turns out to be true.
I’ve made a purchase using my credit card but it is impossible to get a bank statement for the year 2011 now.
There is no information about this purchase on my email also.
Does anybody have any idea how to find out what was the site and where the BTC now ?
This is another dead end;
Maybe it is possible to analyse all the Bitcoin blockchain blocks for feb.-march.2011 and to select those who contains the sums near to 100 BTC ? And then we can try to find the owner of the bitcoin adress where the funds were transfered to... Is it real ?
You remember the popular phrase
”not your key, not your coin”? that’s what best explains this situation. It will be impossible to analyze the transaction since it was never made because you purchase it in your cex account and all that was displayed in your account were just number not real bitcoin so unless you moved it to your non-custodial wallet you won’t be able to get anything by analyzing the blockchain chain.
And aside from that; if your come across a transaction with 100+ bitcoins it does not automatically mean that’s your transaction, there is a high probability of people transacting that amount since the value was not substantial back then so this is also another dead end.
The reward of 10 BTC will be distributed in case we find this BTC.
This reward is quite enticing with the current price of 1
BTC but until you come up with a better lead on this case I’m afraid nothing can be done for you.