First of all keep in mind Latvia is not a hot country, and there are quite a few people with black skin living here because of that. Even now, in Summer time, the temperature doesn't go above 25° by Celsius too often. Usually it's about +20 ... +25 in Summer and from - (minus) 10° ... +5 in winter times.
Job? Oh well. There is total unemployment these days. Even many root citizens of Latvia lost their constant job, what could we say about foreigners, specially from Nigeria?

No chances at all...
As far as I know, in Latvia there is no Nigerian embassy. The closest one is located in Ukraine. Type "
nigeria embassy latvia" in any search crawler and you will find the address.