All my export presets have disappeared in Lightroom???? And if I try to recreate them they don't save they just disappear again.
Have you clicked on the "User Presets" Triangle to show/hide?
Have you opened a new catalog?
Have you searched for the Presets folder? ( Preferences > Presets Tab > [Show Presets Folder] )
What do you see in the Export dialog? A screen-clip?
Retrieving data ...