This is a popular time of year to be moving, whether you are an expat, or just changing flats. I just thought I would post a few helpful hints based on my both my professional (relocation consultant)and personal experience (over 20 moves)to get you through the stressful ordeal of moving.
If you have professional packers coming in, while this might appear to be a dream come true, it actually involves a lot of preparation. They will pack
everything in sight unless instructed not to, so carefully sort and mark what is not to be packed. Even something like a TV cable could belong to your house, not you. That's not a big deal, but packing documents like passports, arline tickets or travel papers is, not to mention medications.
Don't wait until the last minute to look for all the keys you need to return to the owner. If you have small kids, you might have put away their room keys so no one locks themselves in their room.

Take the keys out of hiding. Tape them to the top of the door frame (with non marking tape)If you are missing a room key, this is not a disaster. First check to see if any of the other room keys fit that lock. Unlikely, but worth a try. If not, then look for the number on the door lock and you will need this number to get a key. If there is no number, if you live in an apartment and you know any of your neighbours, ask them if you can try their room keys. You might find a match and then you can just take the key to get a new one. When you return their key, take a bottle of wine, or chocolates with you. A room key will cost 10 - 15 chf. If you don't find a number, or a neighbour, you will have to pay for the landlord's time and trouble to find a key. On your inspection report when you took over the place it should have been noted if any room keys were missing from the start so check that first to be sure you don't go looking for what never existed.

You might discover you haven't lost any keys.
If you lost a mailbox key, you can make a copy as long as it is not a security key. Most key places have mailbox keys. Try and get one that looks as close to the original. (square or round style) Mailbox keys cost 12 chf approximately.
House keys are a much bigger problem as they are almost always a KABA key. Your lease will say how many keys you have been given. You cannot make a copy of the KABA key unless you have the id card from Kaba so you are going to have to go through the owner on this. Best to come clean. If you live in an apartment and your key opens common area doors as well as your own, you don't need to pay for new cylinders for the common doors. What you need to do is pay for the replacement of your own unique lock(s) and the correct number of keys. The new key number will surely almost be the same as the original key, but will vary. For example if the key was xyz1234 the new key will be xyz1234-1. It will open the common doors and then your new lock(s).
Keys are a very big deal here so don't underestimate how serious this will be taken. Some leases specify a blanket figure for key replacement, others it will be the actual costs as per the invoice. They will deduct this from your deposit.
There are numerous other tips I could pass along but over the years these are the two things that almost always seem to come up with my clients.
Happy packing!