I found out that my Email provider has closed my Email because it was not in use.
I'm also unable to re-register with the same username because it is blocked.
I tried to change Email address to a new one but I'm unable to do so because it is sending a request to my old Email which is closed.
What can I do to change my Email address?
If you have lost access to the email and are unable to re-create it, you will need to do a full recovery on your RuneScape account in order to get the registered email changed to a new one.
Jagex need to see proof that YOU are the true owner and creator of your RuneScape account before they will make a change as important as resetting the registered email.
When you are on the screen that tells you an email has been sent out to the old email, read further on and click on the hyperlink
'contact Jagex support'
. This hyperlink will take you into the recovery system.
Before you start, login to the game and talk to Hans in Lumbridge. Hans will tell you exactly how old your account is so you can calculate the month/year of creation, an important piece of information for the account recovery form.