Let me guess, it was playing just fine before winter and you just picked it up to discover none of the notes play anymore. Anywhere. The strings are frapping out all over the place. Nothing but buzz. What happened? Did someone sit on this thing or something? Does it need a setup?
I can't tell you how many of these I see every winter, it's really astonishing! If you guitar sounds like the description above, it's probably completely dried out! As most acoustic guitars dry out, a hump rises where the neck joins the body and the top of the guitar sinks in. As the top sinks in, it pulls down the strings with it, which is why the action drops sometimes so low that the strings are ON the fretboard. Sometimes you catch it early, and you just find the buzz at the 14th fret area.
What to do about it: Get an in-case humidifier and check it weekly! I use 2 on every guitar I have and that seems to work relatively well for me. There's an article I wrote a while back http://www.jhaven.ca/2/category/humidity/1.html as well an excellent article from Taylor Guitars here http://www.taylorguitars.com/global/pdfs/greatest_hits.pdf.
If things are really bad, I'd go to the grocery store and buy some sponges and ziplock bags. Grab a couple bags, punch holes all over the bag and stick a moist sponge in each (make sure to squeeze them out so they're not dripping) and put one in the soundhole, the other at the neck joint or up by the headstock, and close the case. Each week, get the sponges wet again. You'll begin seeing an improvement anywhere on average from 2-4 weeks.