Ok, I answered my own question.
Answer is: backup table wp_snippets to SQL file (data only)
Remove the code snippets plugin
If you want to live dangerously, re-install and activate plugin, then run the insert code from SQL file (PHPadmin or any other way)
If you want to try safer ways to run PHP, get your lost code snippets directly from SQL file.
Personally, I love the orderly snippet interface, but from now on I’m going with my old, trusted, “always-there” custom PHP files.
Good luck