The update or upgrade both just stops
Thanks for your reply. I tried both the terminal commands, the update or upgrade seems not to respond after 5 or 7%. When I tried the upgrade option, it showed 30 minutes remaining, then suddenly it stopped and after few minutes it showed 20 hours remaining then again it stops for a more than 5 minutes, then it shows 3 hours remaining. It either does nothing or it only shows different times with only few bytes of data been download. This is only with Ubuntu's update or upgrade from the terminal command. There is no issue with other file downloads using my high speed Internet connection. Please do tell me if there might be anything else blocking the download for the update or upgrade.