Near-infrared spectroscopic observations are necessary for the chemo dynamic exploration of the dust-ridden regions of the inner Milky Way (IMW), where most of the Milky Way mass lies since high dust extinction prevents optical studies. Additionally, the stellar probes used for the chemical investigation of the IMW need to be bright. M giants are the best candidates for this since they are ubiquitous, brighter, but cooler (Teff < 4000 K). Due to large uncertainties in photometric methods, a method to determine the stellar parameters for M giants from the near-infrared spectra themselves is needed. Such a method would thus open up the possibility of efficiently allowing IMW regions to be analyzed. Furthermore, there are several unexplored absorption lines of various chemical species in the near infrared spectra, but a reliable linelist is needed to use them for abundance determination. In this talk, I will introduce a novel method to estimate stellar parameters of M giants using high-resolution (R~45000) HK-band (1.4-2.4 um) IGRINS spectra. I will present the detailed validation and testing of this method using nearby M giants and APOGEE stars. I will also show the elemental abundance trends versus metallicity for up to 22 elements determined for solar neighborhood M giants using our well-tested HK band line list. Further, I will present the preliminary results from the application of this method to determine stellar parameters and elemental abundances for seven M giants in the inner Galactic bulge and 20 M giants in the NSC. Lastly, I will compare the IMW abundance trends versus metallicity with those from solar neighborhood stars observed with the same instrument and analyzed, in the same manner, using the same line list to investigate the similarities/differences in IMW stars compared to those in the solar neighborhood.