Done it thank goodness
Thanks Brian, I've reuploaded every powercms file except for localhost.php and wa_globals.php and its still works (or not works) exactly the same.
Then I went back to basics, thought what would happen if I made a new page in the middle of the 1 to 16 pages I can see.
This made 16 appear lower down the page so I thought it seemed that it stopped viewing from 16.
Deleted page 16 and it then all worked correctly. So obviously there was corruption there, I re added 16 all fine.
What a relief, thanks for your time.