Hello Customer, and welcome back to Just Answer.
You will need to contact your airline, EasyJet, to cancel your flight, explain the reason why you wish to cancel, and ask for a refund. You can view the airline's refund policy and contact EasyJet Customer Service, with the information provided here:http://easyjet.custhelp.com/app/answers/detail/a_id/4057
They don't ordinarily give refunds unless you cancel your flight within 24 hours of booking it. However, if this is an 'extraordinary circumstance' beyond your control (the riots/strike), you might have a better chance.
The phone number in the UK given for cancellations is 0871(NNN) NNN-NNNN
I wish you much good luck!
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