Yes, they can often be improved, but not fully “fixed.” High ISO noise can be reduced in software such as Lightroom or Photoshop, and edits like contrast, black/white point, tone, and color adjustments can make some images look better. Cropping can also help by removing distracting or blown-out areas.

But software cannot restore detail that was never captured. If the files are noisy, mushy, soft, or have blown highlights, those problems can only be reduced, not eliminated. You should expect cleaner-looking results after denoising, but not crisp, low-ISO quality.

Best approach: pick the most important photos and have them professionally retouched, since selective editing may produce acceptable keepsakes. If there are key shots that cannot be salvaged, consider a reshoot for portraits with a more capable photographer.