Why cant we create wormholes and black hole??
There is too little knowledge about them.
Black holes are a mystery of the galaxy. There is very little knowledge about them, all we really know is that they are "a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it" (Wikipedia). Although we may know that, there is much controversy about them. In 2016, scientists did however create a small artificial black hole. Check out this site for more information on that small black hole.
Wormholes however, are just hypothetical. There is no proof that they truly exist.
We don't have the technology to create either.
Wormholes are theoretically possible. General Relativity allows an Einstein-Rosen bridge which connects two regions of spacetime. The problem is that to open the moth of a wormhole so that something can pass though it requires and exotic form of matter. This type of matter has never been observed and may not exist.
So, that is why we can't create a wormhole.
A black hole is a region of space where a mass has been compressed into a region less than its Schwarzschild radius
The only thing which is known to be able a massive body into a black hole is gravity. We would have to create a body as massive as a large star to allow gravity to collapse it into a black hole.
It is theoretically possible that a particle collider such as CERN can create tiny black holes. If these were created they would evaporate in an instant. Such black holes would have a very specific signature which has never been observed.
Scientists have made something which in some ways behaves like a black hole. It was however not a black hole.