Five asterisks doesn't mean that there are five missing letters, it could be any length - the number of asterisks that show is fixed.
If you can't reset the account's security questions contact Support in the country where you are (and which is therefore the country on your account) and see if they can reset them, and re-enable the account, for you : Contact Apple for help with Apple ID account security
If your country isn't on that page try this form to contact Support : https://www.apple.com/emea/support/itunes/contact.html