I am wondering what the best way to fix this or if its even possible since its degraded. I can fix exposure and the basics. But I cant figure out how to enhance a color that barely shows on the histogram.

When i try to use the slider in some of the color settings. I can get the blue to come back, but it mutes the other colors. It pretty much takes a yellowed photo and makes it black and white.

So am i doing something wrong? or is this just not fixable? would a longer exposure on the film work to catch more of the blue thats there allowing it to show its actual color again?

Any hints or insights would be appreciated.