Check your IP address through command prompt.
Your IP address should start with 192. If it starts with 192 you have a valid address. If it starts with 0.0.0.0, 169 or its blank, you need to get a valid ip address.
A couple of things to try -
- switch of router and computers then switch back on again.
- delete the profile in network settings.
- in command prompt type ipconfig/release then type ipconfig/renew. This forces the network adaptors to drop and renew addresses such as ip address.