I can’t see other PCs on the network

I have a home network with 2 other PCs, and we all operate windows OS but different versions (I use windows 7 but they use XP), now I can't see other PCs or even access them on the network even if I wrote the IP of that device in the address bar.
Taking in consideration that we all have a shared internet connection and it is currently working smoothly.
When I type the IP address of the PC, I get this picture:

Error:
Windows cannot access\192.168.1.22
Check the spelling of the name.Otherwise,there might be a problem with your network.To try to identify and resolve network problems,click Diagnose.
