Try mo muna ipconfig /all. Then compare the results with other PCs that can browse the Internet. If not the same, try mo Ipconfig /relese then IPconfig /renew to get a new IP address from your DHCP server.
If the IP address starts with 169.xx.xx.xx then your PC was not able to communicate with your DHCP. It is an IP address assigned by its LAN Card or APIPA.
Then IPConfig /flushdns to flush out the old DNS entries in your cache memory. Then try mo ping www.yahoo.com to test if your PC can indeed resolve FQDN or Fully Qualified Domain Name. Otherwise check your DNS and Gateway addresses if can be reached by your PC.