Q: Do virtual particles violate the laws that energy can be created or destroyed? Have virtual particles ever been observed? In any other instance can energy ever be destroyed or created?

Physicist: Almost. There’s a version of the uncertainty principle that says that the amount of energy and the amount of time involved in an event can’t both be certain.  You can think of this version of the uncertainty principle as the universe making clerical errors.
Generally a virtual particle will pop into existence, do whatever it does, and then pop out before the universe catches it.
For example: the gluon (pronounced “glue on”) is the virtual particle that holds the nucleus together. But the time that it can exist is so short that it can’t even get from one side of the nucleus to the other. This is a big part of why big atoms fall apart (uranium, plutonium,…).
Unfortunately, only “real” particles can be measured. Virtual particles have to be inferred. We can observe gluons by introducing enough energy that they don’t have to rely on clerical errors to exist (I’m talking about particle accelerators here).  But virtual particles can only be detected in terms of the effects they have on other particles (like holding an atom together).
Aside from the uncertainty principle, everything obeys conservation of energy. And even with the uncertainty principle the extra energy gets ironed out faster than you can blink.