Changes not being saved

For some reason, any changes I make to existing posts or pages are not being saved.

They’ve appeared on the site ok, but if I go back into the same posts now and try to add a link or a picture, the changes are not saved.

I click on the “Save” button and the site loads up (rather than just the admin area), but new pictures or links aren’t there. Even if I hit refresh or go back into edit the page.

Any thoughts/ideas would be really appreciated