If your trip hasn't been cancelled but you for some reason don't want to travel anymore, your tour operator is not obligated to give you a refund.
What you can try to do is to contact them and see if they can rearrange the trip or if you have travel insurance, if they can cover it for you. Also, you can try to get the money back from your bank.
IMPORTANT NOTE:  In some cases, you will lose your deposit, and in other cases you might still need to pay the full amount. That's why it's so important to read the terms and conditions beforehand.