I had an account linked to Steam, but I forgot my password and can't find it

So I made a new account, but I couldn't connect it to Steam. 

my old account is 'sisisi112' and connected steam account is Sino

You can just reset your password with the e-mail-adress that is connected to your account. During login you have to click at something like "Forgot your password?". Set a new one and log into your old account.