The word "unfortunately" is an adverb that we use when an action or a situation is not good, or we feel sorry that something has happened. It’s often used as a transition when going from one sentence to another:
Lewis would like to stay home today; unfortunately, he has to go to work.
Helen is a great worker, and she’s very enthusiastic about what she does. Unfortunately, the company she works for has to lay her off because business is down.
There are, unfortunately, very few days left for us to be together.
We need to get a new refrigerator. Unfortunately, we can’t afford it right now.
Pedro was going to go to the park and play baseball with his friends, but unfortunately it’s raining.
He wants to go to school today; unfortunately, he’s sick.
If you drop the "ly" ending, this word becomes an adjective:
This is a very unfortunate situation.
It’s unfortunate that they can’t come to our party.
Donna had a very unfortunate accident and lost some of her vision.
He wants to go to school today; unfortunately, he’s sick.