Understanding the structure of materials under the extreme pressures and temperatures of planetary interiors is essential for constraining the physical and chemical behavior of planetary materials. While the atomic structures of many major crystalline phases are now well established, determining the structure of liquids and amorphous materials under such conditions remains experimentally challenging. However, these disordered states play a central role in planetary differentiation, magma oceans, and melt transport in deep planetary interiors. In this talk, I will present recent advances in probing the atomic structure of disordered materials using X-ray total scattering techniques. The investigated systems range from silicate glasses, which serve as structural analogues of silicate melts, to glassy carbon. These studies provide new insights into structural changes in disordered materials at high pressure. Finally, I will discuss future perspectives for probing melts directly under extreme conditions through shock compression experiments combined with high-energy X-ray scattering.