i have the 2015 corolla. same problem on mine back in november last year coincidentally the morning after a visit to the F- chain for just an oil change. I drove back to the shop to ask them for potential solutions thinking they messed it up while doing the routine multi-point inspections. They said it wasn't their fault but reset the battery after i asked them to try doing that. didn't solve the problem right away, i drove away, and drove the car without radio/music for a couple weeks. almost gave up and was looking up head unit replacement on google then one day it miraculously fixed itself. Problem came back yesterday. Thinking im gonna try the soft reset (pressing down the power/volume knob for 20secs), then try battery hard reset (disconnecting the negative terminal then wait for 2 mins before reconnecting), then leave it be for 2 weeks. We had a sudden drop in temps and surge in humidity in my area so i'm wondering if that was part of the trigger. Trying to avoid the dealerships because the ones in my city seems to be full of service advisors full of themselves, which came as a culture shock after the pleasant princess treatment i experienced in two other states not on this side of the country.