This in on their website:
You may cancel your booking within 24 hours of making the original booking. Please note a cancellation can only be processed up to two (2) hours prior to the flight's scheduled departure time. You will receive a refund (including taxes and charges but excluding any credit card, transfer, speedy boarding, sports equipment, or other administrative fees). A cancellation fee per passenger per journey will be charged in accordance with the table below. Cancellation must be made via our call centre on 0871 244 2366 (calls cost 10p per minute; calls from mobiles and other networks may cost more. For other telephone numbers visit the contact us section.)
easyJet regrets that it is unable to offer refunds in the event of passengers being unable to fly owing to any change in personal circumstances, including but not limited to medical grounds, with the exception of the application of the 24 hour cancellation policy.
In exceptional circumstances, however, easyJet will consider issuing a credit in the event of the bereavement of an immediate family member (mother, father, brother, sister, grandparent or child) provided that the claim and a copy of the death certificate are submitted by post to the easyJet Customer Services Department.