[tai_91]

okay i have a single cutaway montana acoustic and i've noticed that the 13 fret on all the strings dont work only 13 everything after it works fine. and on my g string the fourth fret doesnt work properly either whats up with it?

[ninjato]

Your guitar is seriously dried out and it is fretting out at the 14th fret.

Sighting down the neck from the headstock I'm gonna bet you see these issues:

1: Guitar top above the 14th fret is sinking taking the fretboard at the 14th down w/ it.
2: Looking at the 14th fret there is a "hump"
3: Looking at the guitar at the bridge from the side, you will noticed that it is humping up w/ the angle of the bridge tilted towards the headstock and not sitting flat. \
4: Action at or around the 12th fret seems a little high.

If you got these issues, and your relative humidity index is below 45%, I recommened you get a room humidifier, and set it to 50% and re-humidify your guitar for about 2 weeks. That will hopefully bring your guitar back to life and then you can take it to a shop and have it tweaked.