How refunds work
Each organizer decides their own refund policy, and it is on the event page before you pay. Either refunds are available — up to a set number of days before the show, or right up to it — or all sales are final.
It is worth reading. It is the answer to this question, and you get it in advance rather than in an argument afterwards. Once an event is on sale, the organizer can't change it.
Asking for one
Open My account → Order history and use Request a refund on the order. You can say why, though you don't have to.
It goes to the organizer, who approves or declines, and you are told either way — including whatever they said if the answer is no. Some organizers approve automatically, and with those the money starts moving straight away.
A refund covers the whole order. If you bought three tickets together, all three are refunded and all three stop working.
When the button isn't there
A ticket that has been scanned at the door can't be refunded, and nor can an order where you've sent a ticket to somebody else — refunding it would cancel theirs too. The order says which, rather than leaving you hunting.
The deadline is real
Once you are inside the organizer's cut-off — a week before the show, say — the request closes and your order will say so rather than leaving you hunting for a button.
That window is how long they need to resell the seat, which is the whole reason it exists.
If the event is cancelled
You are refunded in full, automatically. Ticket price, our fee, processing and tax — all of it. You don't need to ask.
Banks typically take five to ten business days to show it.
If the date or venue changes
You can ask for a refund for a while afterwards, even if the event said all sales are final. See The date or venue changed.
If you simply can't go
Where refunds aren't allowed, or the window has closed, you can still send the ticket to somebody else from your account, right up until the show ends. It costs nothing, and it's theirs once they accept it.