So that is a really generic error.. what do you get when you do net view \\servername ?
Your saying you can access all the other shares on this box, just not C$ from this location?
Same issue for \\servername, or \\Servername\c$ or servername\D$...
My concern is only that what is the reason that am not able to access network server from one 2012 server????
let me clear the scenario,
e.g. I have below servers in my organization.
PC1 = Hostname is SCCMwin2012
PC2 = Hostname is SQLwin2008
PC3 = Hostname is webwin2008
PC4 = Hostname is SCOMwin2012
PC5 = Hostname is DCwin2008
PC6 = Hostname is DHCPwin2008
PC7 = Hostname is Serverwin2008
PC8 = Hostname is server2win2012
All above machine in one domain, and can be ping each other, accessing data by using \\servername\**$ (any drive) but but but.
from PC1(SCCMwin2012) can not access data of server PC2 (SQLwin2008). (\\servername, \\servername\C$ any share not working here.) if I do reboot SCCMwin2012 server then only able to access SQLwin2008 data from network.
pls let me know if in case still any concerns.