@Dr_Torabi,
Create nation notes form,
choose personalize button,
go to add context.
You will be available with add,update and delete option.
Hope it may help you.
Please let us know if there any issues.
@Dr_Torabi,
Check the database table customlists,there will be a column named cl_deleted.
If any context gets deleted, the value of cl_deleted of will be updated to 1.
If not then there will be default value 0.
Since you have deleted all the context, all the rows have been changed to 1 and the page does not displayed.
Update the column with 0,refresh the page and you will be loaded with the page.