Do you have an EasyJet flight you cannot use any more? EasyJet will not allow you to cancel your flight (and get your money back). But, do not despair! EasyJet allow flight name changes, which means that you can sell your flight to someone else! You are unlikely to recover 100% of the price you paid, but even getting half of your money back is better than losing all of it.
The name change fee depends on when you make the change. If it is 60 or more days before the day of the flight (for return flights this is the day of the outbound flight), the fee is €21, £15 or $23. If you change the name within 59 days of the departure the fee is €65, £45 or $68.
Change fees are per person, per flight segment. E.g. the change fee for a return flight is double the amounts mentioned above.
EasyJet allows changes to the departure and destination airport. This means that for a fee you can change a ticket from London to Rome to become a flight from Madrid to Sofia. You can also make changes to the ticket dates. The flight change fee again depends on how long before the flight you make the changes. If it is 60 or more days before the day of the flight (for return flights this is the day of the outbound flight), the fee is €21, £15 or $23. If you change the flight within 59 days of the departure the fee is €65, £45 or $68. For flight changes, in addition to the flight change fee stated above, you will also need to pay the difference in price between the cost of the original flight booked and the cost of the flight at the time the change is made. No refund will be made if the cost of the flight is lower at the time of the change.
A lot of people will be happy to buy your tickets from you, as long as you offer them a good price. You will rarely recover 100% of the price you paid (unless the price of the flight has increased significantly and you do not have to pay the fare difference), but even getting 50% back is better than not getting anything!
If you have an EasyJet ticket and you need to sell it, you can go to a marketplace for transferable flights and holidays, where you can hopefully sell your ticket!