Electrics on 2011 Hyundai ix35 Highlander are falling apart

When a bunch of electrical functions all go out at once (or within a short space of time of each other) suspicions are always drawn to the car’s body computer. This computer controls all the functions you mentioned as well as dozens of others from the heating and cooling, central locking, lights, wipers, dashboard and much, much more. When the computer starts to die (as most computers eventually do) these functions will start dropping one by one and sometimes in simultaneous batches of failures. Eventually, pretty much nothing will work and the car will not even respond to the key’s inputs.

An auto electrician is the best place to take the car, and as well as the computer, they will also check the car’s battery and charging system and the quality (or otherwise) of the car’s earthing points. Bad earths can cause similar problems to this, but the body computer remains a likely culprit.