weird.. speakers arent supposed to simply stop working without some warning or sign of damage while it was playing audio.
you'll have to take the speaker apart.
first check to see if the cone moves in and out freely.. if it doesnt, there might be something inside that needs blown out.
the gap can be quite small.. but be sure to have a real good look at the speaker, because the voice coil gap might not be accessable to any dirt or bugs.
usually the woven spider will be glued down to prevent eye contact with the outer surface of the voice coil.
that means, if the voice coil has a vent.. there is a hole on the back of the magnet.
dirt might have gotten into their (but sometimes there is a piece of cloth or material to try and prevent dust)
maybe a bug has chewed through the woven spider and is stuck inside the voice coil.
if you get that bug out, you can use the speaker again.
and if the bug came through the magnet hole.. you can still use the speaker again after removal of the bug.
the quickest and easiest access to the voice coil is by removing the dust cap on the cone.
these usually come off with a hot glue gun (or even a blow dryer.. but the heat output can be quite different)
after you remove the dustcap.. you will see the inside surface of the voice coil.
if nothing is in there.. try moving the cone in and out while blowing some air into there.
if the cone doesnt move in and out freely.. is it stubborn or is it jammed?
you have to listen while moving the cone in and out.
if it is jammed and there is a bug inside, it will probably be jammed in only one direction.. and the other direction should help free the bug.
if the cone is stubborn.. you have to listen for any metal scraping sounds.
the voice coil might have unwound itself from a lack of glue (the glue can get too hot and evaporate.. but since it is outside, it could evaporate with the help of any heat when using bad glue for an outside speaker)
another thing that can happen.. if the voice coil gets abused with too much power, the metal can swell up and rub the sides.
if you have to take the whole speaker apart to look at the coil and see for yourself if there is damage or dirt (or a bug)
try not to cut the woven spider.. use the heat gun to unlock the glue around the edges.
this way, if there is simply a bug or some dirt in there, you can put it back together.
you'll need a soldering iron to remove the tinsel leads that go from the voice coil to the speaker positive/negative.
and you will also need to shim the voice coil.
most speakers have what they call a 'pole piece' that runs up through the voice coil.
you can get some pieces of paper and tear then into long rectangles, then fold them.
each rectangle needs the same amount of folds to keep the shims the same thickness.
two works.. but three can be best.
if there isnt a pole piece, then you should have a big hole in the magnet and can insert the shims through that hole into the outside of the voice coil.
a digital multimeter can also tell you if the voice coil is bad.. but it doesnt have to! LOL
stranger things can happen.. meaning, you might get a false reading if the voice coil touches the metal inside.. or if the voice coil simply swelled up from heat.
i had a tweeter that quit for no reason at all.
it was in my vehicle and was working when i put the few pieces of my car audio system away.. i didnt use the radio for a couple years, and i brought the tweeter into the house and it didnt work anymore.
i can only assume the voice coil swelled up from the exposure to the heat of the summer inside the car.
one reason why 'car speakers' are ment for the car.
but.. maybe the magnet lost its magnet power because of extreme heat or extreme cold.
it is doubtful that a soldered connection came loose, but stranger things have happened.