Ever since the latest OS upgrade (last week) my phone goes into silent mode automatically at midnight every night. I've checked the schedule settings and that is turned off and I've never used it. Anyone else having this? This is a huge issue for me since I'm on call 24/7.
I recommend you backup all your critical stuff and pictures and audio and dowloaded files to a PC. Write down email settings. Forward important emails. Copy down critical contacts. Write down where you've situated icons. Prepare to wipe your device.
Perform a factory data reset.
My last replacement before this one was doing something similar. My quiet mode time settings were set, but not turned on. The update happened then at the time of day that my sound should have returned it always did but never went into silent at the time it was set for. Thing is, I didnt have the mode turned on, only set. So, I'd have the phone set for silent with Quiet Mode off. At 3am the sound would come back on anyway. I had a few other issues with the small update and wound up with a replacement. I thought I was the only one and you are only the second other than me to mention something like this.