Find time somewhere along your journey where you can spend up to 2 hours at either an airport ticket counter or a city ticket office. Any airline should do. As a hand-written ticket, it will probably be a time-consuming re-issue, especially if they have to hand-write the new ticket. In my one experience, even if you have less than 16 segments left and the flights are all e-qualified, they may still re-issue as a hand-written ticket.
Others here might have more specific advice as to which airlines/airport/cities can do this most efficiently. The experience I just mentioned was with BA at CDG for a ticket originally issued by AA. Friendly, just time-consuming, and I don't think it was because of incompetence.