I have a simple question about the theory of evolution in general.
Give me the best top five  mysteries(or unsolved problems) in the theory that we don`t know the answers at all and we will not know at least in the next 20 yers.   

Tnak you in advance !

that is not a simple question and you are asking us to act as soothsayers and crystal ball gazers!

It's not possible to know what will or won't be known next year let alone 20 years from now. In addition it is massively over simplistic to say "top 5 problems" - science, biology and specifically evolutionary biology are way bigger than top 5 anything! Lastly, most scientists would say there are no major problems with evolution. It is no longer a theory since there is overwhelming evidence from so many sources that it is fact.