In 2010, you came across a site that was giving away bitcoins. The site said it was free money so you signed up. You were logging in to figure out how it was money but couldn't. The last time you logged in you had more than 100 bitcoins. Later you forgot about the site until 2017 when a ponzi was advertising Bitcoin. Bitcoin? The name rang a bell and you stated hearing stories. You remembered you must have many bitcoins somewhere but you can't even remember the name of the site. How would you recover your BTC?
If the cause is due to forgetting the website, then the possibility to get back the Bitcoin that you have will be very small. And what's more if you forget the email and password you used at the time, then you can be sure you can't get your Bitcoin back.
Unless you have private keys on a Bitcoin wallet in 2010, you can still recover even though of course it takes a long time with blockchain integration in your wallet from 2010 to the present.