Trying to save work

Does this happen with each file or just the current one? If it happens with the one you're currently working on but not every one, the file might be corrupted. I have seen this recently myself. The way I personally solved it was to copy everything on my timeline, Shift Select and then right click and select Copy Selected frames) then paste that inside a graphic symbol and then close the file. Then I opened a new file and Imported the Library of the troubled file into the new file and then simply dragged the graphic symbol into the new file, then save the new file. Bam you're up and running.