Workgroup list disapeard

hi dear fellows, it is my first time that i am posting my problem here, mostly I got the solution be searching but this is real heakache i got this time…
First i explain my network, i have 200 computers on my network using win2k pro and 3 different servers and 13 workgroups.
Proble is that from last few days i can’t see workgroups in my network places only one workgroup is there and the computer is a member of that workgroup, when i double click on that is saya “WorkGroupName is not accessabel” and “The network path was not found”
while i can ping other computers,i can access from run command \\ComputerName or \\192.168.1.22
maped drives are working properly.
I will be really thank full to my friends for their time and effort.