In order to perform electrolysis, electrons or electricity has to pass through that substance. In order for that to happen the electrolyte or the substance undergoing electrolysis has to have ions.
It is a known fact that usually covalent solutions (e.g sugar, ethanol) does not conduct electricity. It is because they do not have free moving ions to conduct electricity.
Ionic compounds such as NaCl is made with ions. However these ionic compounds are unable to conduct electricity unless the ions are free to move. Therefore in the solid form even with the presence of ions ionic compounds does not conduct electricity. Ionic compounds will conduct electricity
i. if the ionic compound is molten or
ii. if the ionic compound is dissolved in water
As in these both cases ions are free to move.
