Unable to make yogurt in cold climate
Not covering it was unwise - it accelerates cooling and also allows other (unwanted) bacteria to populate it.

Not insulating it to keep it warm was your main problem. I seem to recall that some cultures in cold climates that traditionally fermented milk products would do so in a bag worn next to the skin, under clothing and blankets, to keep the ferment warm at body temperature. You can probably improvise something a bit less primal, but it's there as an option. A well-insulated box is generally simple enough, but waiting until the milk was already cool to "wrap some woolens around it" is too little, too late - you need the insulation to keep the heat in, as it does not warm the milk up when it's already cold.

I have decent success with a 35-37C temperature for a long time (24 hours) - but without a means to hold the milk at temperature (perhaps set it above the warm computer? Carefully!) I'd start in the 45C range and wrap it up in a lot of insulation to hold the heat as long as possible. Aside from woolens, styrofoam or cardboard are fairly inexpensive or even free insulating materials that are widely available. You can nest several cardboard boxes inside each other to make multiple layers for better insulation. If you are making a small quantity of yogurt you can add bottles or jars of warm water for additional thermal mass (wrap them all up together inside the insulation/box.)