In order to get an igneous rock from a sedimentary rock, the sedimentary rock must be melted and then that melt must crystallize.
It doesn't have to. Most rocks exposed at the surface will erode and become sedimentary, but igneous rock that is underground can be remelted and become another igneous rock, or can become metamorphic.
For igneous rocks to become part of sedimentary rocks, they must first undergo weathering and erosion, breaking down into smaller particles. These particles are then transported by water, wind, or ice and eventually deposited in layers. Over time, the accumulated sediments are compacted and cemented together through lithification processes, resulting in the formation of sedimentary rock.
Pressure and heat.
To form igneous rock from sedimentary rock, the sedimentary rock must first undergo metamorphism, where it is subjected to high heat and pressure, changing its mineral composition. Subsequently, if it melts completely, it transforms into magma. When this magma cools and solidifies, either below the Earth's surface (intrusive igneous rock) or after erupting as lava (extrusive igneous rock), it becomes igneous rock.
In order to get an igneous rock from a sedimentary rock, the sedimentary rock must be melted and then that melt must crystallize.
It doesn't have to. Most rocks exposed at the surface will erode and become sedimentary, but igneous rock that is underground can be remelted and become another igneous rock, or can become metamorphic.
To become a sedimentary rock, an igneous rock must first be weathered, and then eroded, and then deposited as a sediment, and then consolidated (e.g. by cementation or pressure welding of grains.) To become a metamorphic rock it must be transformed by heat and pressure, which it can do directly (e.g. granite turning into gneiss) or after first turning into a sedimentary rock.
No. There some very old igneous rocks to be found also it is possible for an igneous rock to become a metamorphic rock. Further, igneous rocks can not be turned into a sedimentary rocks directly. They must first be weathered and eroded and only then their detritus and remnants can be deposited as a new sedimentary deposit.
Erosion Deposition Burial and Cementing
Igneous rock must weather and erode into smaller pieces and grains through processes like physical and chemical weathering. These sediments then accumulate, are buried, and undergo compaction and cementation to form sedimentary rock.
Pressure and heat.
In order for an igneous rock to be changed to a sedimentary rock the rock must be weathered down into, well, some form of sediment (sand, gravel, ect.) and then have pressure applied to it to become a sedimentary rock.
In order to form magma, sedimentary, metamorphic, or igneous rocks must be exposed to high temperatures and pressures deep within the Earth's crust. This process causes the rocks to partially melt, forming molten rock called magma.
Heat, pressure, and/or weathering changes rocks into other forms. For an igneous rock to become sedimentary rock, it would firts need to be broken down by weathering or pressure. (As of now, it's simply sediments.) For it to become sedimentary rock,those sediments must then be pressurized or "glued" together by minerals seeping into pore space and performing a process called cementation in which sediments are platered together.
The igneous rock must be broken down into fragments called sediment and somehow cemented together.
Heat and pressure