Deleted Locale, Entries all gone now
I'm having the same problem for assets and globals.

When craft thinks there are no globals, the entire tab isn't showed.
For the globals i created a new temporary global, so i could access the existing (hidden) ones (they were still connected to one locale).
After that i could open and save them.
After saving they worked for other locales again.

I later found out that setting the admin account to the locale that is working also allows access. Opening and saving each entry works.

Still did not find a solution when content is disconnected from all locales.