Why did wlan0 device disappear?
Is this on a laptop? If so, many laptops have hardware switches that turn of all wireless connectivity. If you can't find it then turn to the manual of your hardware.
On my laptop it is easy to accidentally switch it off.
Maybe the wireless killswitch is still locked.
Then you could try to activate wireless with the help of "rfkill - tool for enabling and disabling wireless devices":
sudo /usr/sbin/rfkill unblock wifi
after that you should check if your device appears via ifconfig -a.
Also check the status of the killswitch using
rfkill list