This thread is resolved. Here is a description of the problem and solution.
Problem: Menu translation disappeared
Suggested following steps and it worked.
1) Take a full site backup 2) Delete the current menu 3) Create a new menu in French(the default language). Hope all your menu items(Post/Page/Taxonomy Terms) are translated into English. 4) Then Sync the menu to English from WPML>>Menu Sync
This is the technical support forum for WPML - the multilingual WordPress plugin.
Everyone can read, but only WPML clients can post here. WPML team is replying on the forum 6 days per week, 22 hours per day.