LAN problems on computer running windows XP

At home I have two computers running on windows XP. Previously, the connection had no problem at all. Now, I encountered this problem which is difficulty connecting it to the LAN network I was using before. I have tried several things but I can neither share files nor gain access to the other computers in the LAN. To Ping the client IP is not an issue but for the host address IP it is a different situation. Please help me solve this issue.
