Why has this been the darkest year of my life? ?

You're totally correct. It's been the worst year of my life and I'm 73. So a very bad year.

Because for you ,you like going out and do whatever you like.

It's dark for you because you have never mastered self-reliance, coming up with things to keep yourself engaged and happy enough without other people around. You're a person who relies on others for your basic social and entertainment needs, so of course it's hard when you're cut off.

This is a time when lots of people are exploring new hobbies or crafts, focusing on getting fitter or thinner, doing charitable acts for others in dire need, teaching themselves useful skills, self-educating for their future, becoming amateur experts at something they love, and all that.

If you focus on what interests you instead of how terribly unhappy and inconvenienced you are, you can probably find multiple things to keep yourself busy and reasonably content with your own company.

Read all the books in a series

Watch all of a particular director's movies

Teach yourself to cook fourteen meals, start to finish

Bake cookies or dessert breads for gifting

Make beer (it's easy!)

Build a box or bookshelf

Paint something that needs it

Deliver Meals on Wheels for people who can't go out at all