I remembered that I had a Bitcoin wallet not long ago and I tried to find my USB key, without success.
Where have you been living all this while that you just remembered you've 100 Bitcoin... In a cave?
Checking how old the Op account is, he might be saying the truth that he lost access to the wallet which he holds that large amount, because there are a lot of early holders who lost access to their wallet as a result of them not believing in it, and as such, they did not take full responsibility for the wallet. Some only started paying attention to the wallet after they discovered how valuable bitcoin has become and how much they will get if they recover the wallet.
op is very unlucky. even though he has 100 bitcoins, he cannot access his bitcoins. There is no greater regret than this. Yes given the age of the op's account his story seems true so I feel very sorry for him. My dream was and still is to own a whole 1 bitcoin but lost them even after owning 100 bitcoins. In case of Bitcoin if someone loses his wallet key he cannot access his wallet any other way. So no doubt he lost all his bitcoins. so sad story