If you have an email that you frequently use and if that email is paired with your account while you made it 4 years ago,
You can do the following :
1) Click on "Forgot password" in the sign in section.
2) They'll ask for your username/email. Its better to type in your email so you can be sure it'll only go to that email, unless type it in wrong.
3) They'll send a reset password link.
4) Click on it.
By now you should be able to figure out what to do, enter new password, re-enter new password, save password.
Now, all you need to do is not forget your password.
Hope this helped