Hello @SLS
If I understand correctly, you found a bag. I would be glad if you give the bag to the train staff or to a staffed counter. Like this we can return it to the owner.
If you mean with this post that you have lost your bag, you can fill out the free loss report on Submitting a loss report | SBB help & contact. We will contact you as soon as we have found your bag.
Have a nice day.
Kind regards, VlaznimA.