Hi @redhanded
The front panel audio ports are connected via a cable from the jacks on the audio bracket to the motherboard header pins on JAUD1 - see [https://download.msi.com/archive/mnu_exe/mb/MAGB660MMORTARWIFIDDR4_MAGB660MMORTARDDR4.pdf|user manual] p.23 for location and pinout.
Check if the cable is securely connected to the motherboard header pins
Assuming that you have a separate mic input and headphones output socket on the front panel you could always try connecting the mic to the back panel mic input ports(see p.15 of user manual) just to check that the mic input is working in the PC.
If the rear mic audio is OK you may have to remove the front panel audio bracket from the case and check that the wiring is all OK to the mic jack.
It could just be a mic jack problem. There's an internal contact in the jacks that sends a signal to the audio controller to let it know when a plug has been inserted or removed - JAUD1 pin 6 = mic detection and sometimes the contact gets jammed and it doesn't work. You'll notice that it's the same for the headphones JAUD1 pin 10 = headphone detection
If you determine that it is the mic jack itself that is the problem it would be quicker and easier to replace the entire [https://www.google.com/search?q=pc+computer+case+front+panel+audio+bvracket&client=firefox-b-d&ei=MxfaY7SRK7CMseMPnJqJKA&ved=0ahUKEwj09qLk6PP8AhUwRmwGHRxNAgUQ4dUDCA4&uact=5&oq=pc+computer+case+front+panel+audio+bvracket&gs_lcp=Cgxnd3Mtd2l6LXNlcnAQAzIHCCEQoAEQCjIHCCEQoAEQCjoKCAAQRxDWBBCwAzoGCAAQFhAeOgUIABCGAzoFCCEQoAE6BQgAEKIEOgcIABAeEKIESgQIQRgASgQIRhgAUNcGWJIWYLUZaAFwAXgAgAGSAogBuxCSAQMyLTmYAQCgAQHIAQLAAQE&sclient=gws-wiz-serp|front panel audio bracket] (examples only) than to find the exact replacement mic jack.