Also check to see if the camera head light is on or off ( cameras tab ) If its on and the camera is close to the subject, and its set to rernder ( render settings check box) then it will make the light set look very washed out. I always turn my headlamp off and if needed use a fill light i can control instead. To sort your situation, load the scene, remove all lights from the scene tab ( if there are any) and also delete the envirments settings from the scene tab too, this should reset ds to the original hdri. From there you can load the lights you want. Another thing to check is under render settings / environment - if your using hdri settings you need to have dome and scene turned on, it might be that something in one of the sets has reset the environment to the day/time of day settings, again this will suddenly make all of your lighting load wrong.