In the age of rapid electronic communications, we are used to staying in touch with relatives abroad. So it can be perplexing and worrying if we fail to receive messages. In some circumstances, the only option may be to report somebody as missing.
Looking for someone abroad is a complex process and can involve major costs. The first thing to do is to contact the nearest police station in Switzerland or call 117. The police will tell you about the possible measures and the next steps you can take. Also get in contact with the responsible local Swiss representation in the respective country.
In developed countries, the international cooperation between the authorities works well as a rule. Looking for missing persons will be even more difficult in emerging nations or high-risk countries. Try to be patient. The search may take longer in some countries.