My friend chewed up my sofa......
If your friend is an unruly dog (which is how this expression is typically used), it literally means he gnawed on your sofa, and ruined it. Dogs or puppies who are bored or mischievous will often chew on furniture.
"Chewed up" as an idiom is also used in this way: "I chew up guys like him for breakfast and spit them out," meaning you consider yourself very tough and you can easily handle any nonsense or trouble "guys like him" give you.
My whole day was "shot".
My whole day was wasted; you spent the day either doing something you didn't want to do, or something that ended up being useless, and now there's no time left to do something worthwhile.
Student or Learner