Hi there. Can't speak for Nigeria, but the Kenyan Civil Aviation Authority aren't that quick at replying to any outside request. However if you want to find out about the aircraft register or an aircraft on it, the application/request should be made in writing. They prefer a written letter, but at a push will take an email addressed to the Director General, for attention of Licencing Dept, at the email address and postal addresses listed on their website.
Unless you have a local man Friday who can go and make a personal approach, what's listed above is the only procedure that will work in the end. Patience is a virtue....