Filing FIR In Wrong IPC

Hello, I am a recent b.tech graduate. I went from my home for one and a half months. In between I didn't contacted to my parents. So being unsure this incident my parents lodged a missing or kidnapping report to the local police station. So for that police took this FIR under IPC 155/18. So after returning me and my father had to go with the medical examination and court procedures of 164 cr.pc. So my question is, is this case falls under this IPC. if not then in which IPC it falls in. is the case could be finished by simply withdrawing the FIR when I am saying I have done that by my own without any others influence or the medical examination and court procedures were necessary for it. and I want to know that, is it necessary for this case to file an FIR or a GD.