I was able to login to my old Stellar account couple of months ago and when I tried 2 weeks ago it is saying wrong username or password.
I know my email and my recovery code, but the system do not allow me to login.
are you talking about logging in here
https://launch.stellar.org/#/login ? (requires username and password)
what exactly the error message? simply wrong username/password?
happened to me too last year, but it resolved by itself after a few weeks...
have you ever upgraded your account succesfully? you will receive an upgrade token
with the token your stellars will be upgraded to lumens, and you need to save your secret key
then simplest lumens account viewer is here
https://www.stellar.org/account-viewer/#!/ (requires secret key)