Hopefully your departure is not imminent. Here's a suggestion: It's possible (likely) that one (or more) of your flight segments was cancelled or significantly changed. In that case, you might be able to use this as an opportunity to get a better flight (assuming a better flight exists).
Before you speak with someone (you probably have some time to kill while waiting to speak with someone, might as well use it productively), "do your homework": go search Delta (and their partners, eg Air France/KLM) to see what flights would work best for you. Note all the details of your alternative flights, jot them down, have them ready when you speak with the agent.
You paid for your ticket, they will get you where you are going; if your original routing is no longer an option, you can request a different routing (fewer stops/layovers, more convenient timing), even if that would cost more if you paid for it today. You already paid for your ticket (it's a legally-binding contract), they'll take you there. Don't expect an upgrade to business class, but if your old routing had two connections and a miserable long layover, but if you can find a better ("better" as defined by you) routing that starts and ends in the same cities as the original routing, you can ask for that and as long as there are available seats, they should give it to you. It'll help if you have done your homework and have all the flight numbers and other details for your preferred alternative. Be nice, ask politely, let them Do The Right Thing. Good luck and don't panic!
