So today after a few sucesfull flights in cold winter weather I tried to put my Inspire 2 to travel mode but it wasn't able to to do that, motor was spining but legs just appeared to be loose and weren't responding to motor trying to pull it up or down. After inspecting I saw, lets call it - screw, unscrewed. I dissasembled the drone to get my fingers to screw it on, but it is harder than it looks and does not come on. Any thoughts? Has anyone else experienced  this? issue?

Never seen this before! But - since you disassembled the rising mechanism that far - here's what you may try to do: use flat screwdriver to turn the screw counterclockwise (thru a hole in bottom) while firmly holding the white plastic nut with a pair of nose pliers. Don't grab the nut by threaded shoulder, only by narrow wide cap at the bottom. Once you undo jammed nut, guide it back into housing metal part and tighten firmly. ATTENTION: you may need to remove the whole rising mechanism to do it properly. Here's how to remove this assembly:

Once the arms lifting mechanism is assembled, turn the screw manually into landing position (not too tight) and put it back into Inspire frame. Good luck!