Many thanks for your message. I've tried the instructions on that page and to fully re-set my password, have logged in, gone to Update Settings, then Account Details, but when I click Account Details, I get the following error message, so am unable to change the password:
Oops, looks like something's gone wrong on our side.
Please try again
I really don't know why or how the account has been locked as the correct password has been used on both my phone and computer (as it's stored in the mail programme). In addition to this, I can't log on via the web browser access, so I don't know what is happening.
Any further advice would be really appreciated as the email has now been inaccessible for over two days.