A washed out photo is usually fixable up to a point, and the point is worth knowing before you spend time on it.
Areas that are merely too bright still contain detail, and pulling the brightness down brings it back. Areas that are pure white contain nothing at all. No adjustment recovers them, because there is no information left to recover, and pushing harder just turns white into grey.
Contrast is usually the real fix. Overexposed pictures look flat because everything has been pushed toward the bright end, so the difference between light and dark has collapsed. Restoring that separation does more for the image than brightness alone.
Work in small steps and compare against the original. It is easy to overcorrect into something that looks harsh and artificial, which reads as worse than the washed out version you started with.
No. Pure white areas hold no detail to restore.
Brightness down slightly, then contrast up. Contrast usually does the most work.
No.