So the other day I was trying to tune my A string on my acoustic up to a C for a song (Rylynn by Andy Mckee), when the tuning post kinda popped and the string went flat. I thought nothing of it and just stopped trying to tune so high. But now I'm just trying to tune back up to the A, and the tuner keeps popping/snapping/loosening(?) when just trying to tune to that.

Is there a way I can fix this?

Any help would be appreciated.
All you need is yo' fingers and the strings
Did you replace the string after that happened? If not, the string simply broke. I highly doubt that you would break the tuning post before the string...