The Swiss authorities online
Have you lost your residence permit? Has it been stolen?
Report the loss of your residence permit to the police. They will then issue you a notice of loss.
Bring your passport, a passport photo and the notice of loss to the local resident registration office in the commune where you live. You will be charged a fee for issuance of a duplicate or a new residence permit.
If you later find your lost residence permit, you will need to bring it to the local resident registration office to have it invalidated.