New PC, now access limited

Hi, I’ve changed to a new PC and now my access is limited, I can log on fine and write posts, but not edit old ones (although I can edit new ones I’ve made since changing PC) also I can no longer change the presentation nor access such backends things as the WP-Cache, users etc, all I have access to is ‘Write’, ‘Manage’ but only new stuff, ‘Profile’ and ‘Comments’ (and I can no longer seem to edit these).

Any help would be welcome