Sharing Tab is Gone on ME Desktop

My desktop has been in place for a number of years sharing files and
printers with 2 XP machines and another ME machine problem free. All of a
sudden I cannot access my other computers or printers. The files are
visible in network neighborhoood but I receive an error stating that the
computer cannot gain access to the network. My other computers can no
longer access this computer's files or printer.
Here is the kicker-I have gone into network settings and installed and
uninstalled file and printer sharing thinking this might help-This was a no
go. I noticed today that if I right click on the folders that were
previously shared the sharing tabs are gone. It is almost a thought the
printer and file sharing setup is not in place. Note: My cable internet
access works fine and I have tried replacing my network cable to see if this
was faulty. I have also tried hooking this computer up to another network
and experienced the same issue.
Your help is much appreciated...
Thanks
David