Theme not working

Hi I have an old site that runs catch box pro, ive lost the ability to edit pages or customise the theme i thought it was because the licence had expired so just bought new licence but the same issue, if i select customise none of the left menu is there and if i try and edit the pages they are just blank site still works and looks as it should but i need to make some changes Cornercottageboarding.co.uk any ideas thanks