The Fix of all Fixes for s19000 wifi connection failure
Instructions to manually override the wifi dhcp settings of your phone. It should connect again. (Had the same problem with my s19000, what a pain!)
Tap - Menu - Settings - Wireless and network - Wi-Fi Settings
From here tap the left menu button (hard menu)
Enable "Use static ip"
Now, to set up the manual ip you need to go through and fill out ALL the entries below the checkbox. (ie Ip address, gateway, netmask, dns 1 & 2)
To get those values = On your PC - Click start - Type cmd and hit enter - type ipconfig -all
This will show you what settings you need to enter into your phone.
Make sure you select and IP address on your phone that is not used by any other device or your pc. Just select something in the far end of the dhcp range.
Good luck pplz