Apparently galaxies tend to these issues.
(try this first)
There is another solution and that is to try to use the Allshare play app, apparently when it loads it asks you which network you want to use and clicking on yours makes the phone work on your network again.
If that doesn't work well your screwed in regards to ever using the wifi outside of your house. Now some things you might want to do before you do this solution.
1: Enable DHCP on your router if it is then ignore this.
2: Disable Static IP on your phone if it is then your completely screwed for getting wifi networks outside of your living conditions.
How to fix the issue using static IP. (this will only work for your home)
(Make sure your phone is fully updated before doing this to help ensure success)
This is not from me but from
You must be registered for see links
Go to Settings >
Wi-Fi >
press on your connection for a second, a pop up will appear with the options "forget network" and "modify net configuration" >
select - modify net configuration >
select - show advanced options >
minimise the keyboard >
select - IP settings >
Select - Static
Now enter the settings below (make a note of the ones already there in case you want to change back)
IP - 192.168.1.253 or 195.168.1.253
Gateway - 195.168.1.1
NPL - 24
Netmask - 255.255.255.0
DNS 1 - 8.8.4.4 or 8.8.8.8
DNS 2 - 4.4.4.4
And save.
Press the Home button and now try to connect.
Good luck hope it works because I don't even completely understand static IP addresses and I was a cell phone technician lol