If you are in Guinea-Bissau then note that the US government does not have an Embassy or any other diplomatic presence in Guinea-Bissau. If you need assistance while in country then you should contact the US Embassy in Senegal.
US Virtual Presence in Dakar
Address: BLO (Bissau Liaison Office) Edifmcio SITEC, Rua Josi Carlos Schwarz 245, Bairro d’Ajuda
Telephone: (221) 33-879-4000
See also see the US Embassy in Liberia as well as the US Embassy in Kenya and the US Embassy in Mauritius.