How the bag got "wet" can make a difference.
If it was rain or spilled water or a brief dunking in the creek, chances are the down itself isn't all that soaked, because down absorbs water only very reluctantly. (Try hand-washing a down bag at home in the bathtub. You pretty much have to walk on it a while in the tub water, to get it wet enough.) So if it was rain or a spill, it will dry out pretty quickly by airing in the sunshine and fluffing, or even by continuing to sleep in it--it will dry from your body heat. Takes a couple of nights.
If the insulation got soggy because of prolonged rainy cold conditions that create an overnight dew-point within the insulation with no opportunity effectively to dry or air the bag during the day for a number of days, then I guess you have a problem. This has been discussed from time to time on these forums, in greater technical detail than I can offer. *But* the conditions described are unusual, at least for us recreational users. Even in the Pacific Northwest. Where I lived and backpacked for several years. With a 1970 Gerry down bag that lasted me for 20 years and never had "wet down" problems.
Washing a bag at home. A front-loading washer will not tear up a bag like a top-loading agitator washer will. The companies that make special down-washing substances (Nikwax, et al.) will tell you that normal laundry detergent damages the down. I take their word for it. They even recommend that you run an empty, water-only, wash cycle before running your bag, to remove residue of previous detergents. As noted above, you can also wash the bag in the bathtub, but this is a tedious process, and you don't get a spin that way. No spin=significantly longer drying time.
Whatever you do, don't pick up the soaking wet bag without supporting its entire length, or the heavy wet down (supposedly--it's never happened to me) can rip the baffles.
You can dry the bag completely in a medium dryer with a clean shoe or something to break up the down. It takes a while, several cycles. Seems quicker in laundromat machines, but still takes a long time. When you first take the bag out, it's all warm and feels dry, but give it a few minutes and feel around, and there will probably still be damp clumps, requiring more drying time.
You can dry the bag to completely dry fluffiness without a dryer at all. Takes about a week in low-humidity weather. After washing, lay it out flat and supported, outdoors, perhaps lengthwise on a shaded porch railing, until it no longer drips and the shell is dry. Then bring it inside and lay it out in some low-use part of the house, draped over furniture or something. Once or twice a day, shake it, feel for down lumps and spread them out, and turn it over. This takes a looooong time, but if you are between trips it doesn't matter. And it beats spending an afternoon in the laundromat. Eventually you will have a lovely, fluffy, clean, dry down bag.