Help! I had photo negatives in a box that was accidentally left outside. Can they be saved?

The box was on a porch that leaked and then covered with a tarp and forgotten. They have been out there in the weather for a year or so and the tarp blew off. I had a lot of other things going on and forgot about the box and what might be in it. The negatives are in sleeves but look dusty and dirty and like there are some water spots. Is there a way to clean them? I am not sure I have the photos and if there is a picture I would like off the negatives I would like to try and clean them as best as possible then have one or two developed to see how they turn out. I don't want to waste to much money. I usually took pictures of things that mattered to me so I feel like they may have something on them meaningful to me. The pictures were not with the negatives so I may have just had the negatives developed and not the pictures. So how can I best get them back to their original condition? There were also some fine linens in the box, any chance of saving those too?