If anyone, as a private citizen, deprives another private citizen of life, liberty, and the pursuit of happiness, their rights have not been violated?
No. Your constitutional rights are those rights found in the Bill of Rights and later amendments. The "right" to life, liberty and the pursuit of happiness are flowery words found in the Constitution but basically do not amount to anything of substance or legal relevance.
If a private citizen breaks into someone’s house because she thinks there might be something of hers, no rights have been violated?
No - not constitutional rights. In your scenario, statutory laws have been violated. Those laws exist to protect fundamental rights. But, again, we're talking about constitutional rights.
“The “right” to life, liberty and the pursuit of happiness are flowery words found in the Constitution”
Life, liberty and pursuit of happiness are found in the Declaration of Independence not the Constitution.