My laptop can not access into internet by Wireless. I check wireless is good connection. I ping IP address, send 4, receive 0, that mean ping is fail. I did ipconfig/flushdns, error message came out " could not flush the DNS resolver cache". Now I know I need reset IP address or clear DNS cache to get back to access internet. How to clear DNS cache or reset IP address ?

ipconfig /release ipconfig /renew ipconfig /registerdns Also what are you trying to ping? Have you tried to ping your gateway? Do ipconfig /all and see what your gateway is. Also make sure that you have a valid ip address. I like long walks, especially when they are taken by people who annoy me.

Thank you buckethead (by coleg) I did ipconfig/release, renew and flushdns, all there are ok. I ping default gateway, it is passed. I did network diagnostics, it showed IP address 192.168.1.74 (failed), pinf sent = 4, received = 0. But I had other pc with same ip address, this pc can access into internet by wire and wireless. How to fix this problem ?

Are you saying you have 2 PCs with the same ip address on the network? If so, that's your problem right there. I like long walks, especially when they are taken by people who annoy me.

IP address of the pc can access internet is 192.168.1.70 IP address failed of pc can not access internet is 192.168.1.74 I checked default gateway and DNS servers had same address. I ping 127.0.0.1, it is ok - sent=4, received=4. I also can ping gateway But I ping 192.168.1.74 or 192.168.1.70, it is failed -- sent=4, received=0.

Might be Windows Firewall blocking ICMP requests, try disabling firewall and trying ping. I like long walks, especially when they are taken by people who annoy me.