how to reset your network settings to default(tcp/ip settings) in xp

The reset command is available in the IP context of the NetShell utility.
Follow these steps to use the reset command to reset TCP/IP manually:

• To open a command prompt, click Start and then click Run. 
• Copy and paste (or type) the following command in the Open box and then press ENTER:

    Cmd
    At the command prompt, copy and paste (or type) the following command and then press ENTER:
    netsh int ip reset c:resetlog.txt
  
Note If you do not want to specify a directory path for the log file, use the following command:
    netsh int ip reset resetlog.txt
   
 Reboot the computer.

When you run the reset command, it rewrites two registry keys that are used by TCP/IP. This has the same result as removing and reinstalling the protocol. The reset command rewrites the following two registry keys:

SYSTEMCurrentControlSetServicesTcpipParameters
SYSTEMCurrentControlSetServicesDHCPParameters