Postgresql id serial sequence default value restoration

postgres_id_default.sql

ALTER TABLE {tablename} ALTER COLUMN id SET DEFAULT nextval('{tablename}_id_seq'::regclass);
-- replace {tablename} with the curly braces with the table name
-- the sequence name is generally in the form of {tablename}_id_seq but it can be anything, check in pgadmin its name
-- some softwares accidentaly delete this while doing some table operations