Change the software source to main server or dhakacom, then try to update. See this video[1].
[1] https://www.youtube.com/watch?v=Ooy-IckhEYA ---------------------------------------------------------- Dedicated Linux Forum in Bangladesh <http://goo.gl/238Ck> 2048R/89C932E1 <http://goo.gl/TkP5U> Mozilla Bangladesh +880-1611151550, +880-1971151550 -- Ubuntu Bangladesh https://lists.ubuntu.com/mailman/listinfo/ubuntu-bd
