Why did the Mamluks, Ottomans or any other rulers that ruled over Egypt not reveal much about Ancient Egyptian history? Were they not interested, did they not have the tools for extensive research or maybe were they demotivated due to religious reasons? Thank you!
Before Napoleon, Egypt was incredibly unstable. The average life expectancy or time in office before being deposed (whichever came first) for an Ottoman governor was something like a couple years. So the stability of the region overall wasn't exactly conducive to academic research.
On the other hand, and remarkably, perhaps even uniquely in world history, Napoleon's military expedition brought with it a huge number of scientists, linguists, artists, historians, archaelogists etc.
They founded the Egyptian Institute in Cairo, which still exists although it was badly damaged by a fire in 2011.
Their findings were published in a huge collection over multiple volumes detailing the entirety of Egypt from it's botany and biology to its culture and art. Those publications, in addition to the discovery of the Rosetta stone which allowed for hieroglyphics to be deciphered for the first time, triggered [Egyptomania] (http://en.wikipedia.org/wiki/Egyptomania) a frenzy of interest and discovery.
At the same time, the 19th century post-Napoleon saw the emergence of remarkable political stability and advancement under the Muhammad Ali dynasty, which filled in the power vacuum following Napoleon's withdrawal.
edit: word and a link
For one, and this is quite well known knowledge, they found the Rosetta stone.
Before this Egyptian Hieroglyphics were largely indecipherable.
With the discovery of the stone, hieroglyphs could now be translated and understood for the first time since about the 5th century AD, when the last writers of the script likely died out. (The Romans had closed all non-Christian temples in 391 AD, and the last inscriptions found are dated 396 AD)