That information you are giving is what we are already doing. I've factory reset my phone 3 times and it still plays videos fast and there is no audio for anything including phone calls. I've also noticed that you can't record video. Let's admit that something in the last update has messed up some phones. Samsung is having me send in my phone to fix it so I suggest others contact them to do the same. Unfortunately these message boards are full of people who know nothing but reseting a phone. If you don't actually know how to fix the problem please do not respond and waste our time.
I have the excact same problem on my samsung galaxy a50, here is what i tried and nothing works
1) restarting my phone sometimes helps but it stops after a few minutes of i turn my phone off
2) factory reset does not work
3) i went to a store they said it was a chip and they "fixed" it for €75 but after a day it didn't work again
4) for a while when it did work i just played music all the time while the sound was off this seemed to work but it is not efficient
The weird thing however is, i'm from the netherlands and this problem occured a few days before i went on vacation to spain. The problem at home occured very often, but when i went to spain for 2 weeks I had no problem at all. That is when i realised I might know what the problem is. On vacation i barely used my earphones with strings but at home i use them all the time and most of the time when I unplug my earphones the problem starts acting up so my theory is that the earphones and the problem go hand in hand
I still haven't figured out how to solve it, but maybe this will help for some people
Had the same issue on my A50 until I found this video on youtube (https://youtu.be/man7d6kBPOM?t=66). Step 3/5 is what helped me. Basically you have to press power button and volume down key until it restarts compeletly.
Hope this help
Hi my galaxy a50 is also having this problem. I read some replies that suggested resetting phone woth volume down and power and a yotube video that was taken down. I tried all these solution but to no avail. Did u ever find the solution for this?
Did anyone find a fix for this? I bought my son the phone and after 8 months, microphone has stopped working and the phone is playing all videos 4x the speed and like you with no sound. When Samsung came to repair the microphone issue, they said it had water damage but I know the phone hasn't been in water! I read on other forums that when Samsung engineers came to repair issues on their phones, they all reported water damage. The phone has become useless after 8 months! My older son is a massive fan of Samsung phones and he's tried all the fixes suggested with no joy.