I had the same issue. I was able to fix it by editing the config file via putty from my computer (using ethernet for the connection of course). Whenever I typed my wifi-password in, it was gone the very next moment, so was my ssid. I was able to fix this by doing the following:
connect your Pi with your desktop-computer via ethernet
edit the config file manually by
typing in your ssid, your
wifi password and setting
wifi.enabled=1
remember 2 things:
delete the ";" infront of those lines, thats the reason why it didnt work for me the first time
after you get an recalbox update, the config file is
NOT getting updated automatically (as far as I can say), thats the reason why it didnt work for me the second time 🙂
I hope I could help.