While the C$ admin share is widely discussed, any current firewall, even the one from Microsoft will block access to that. And if you didn't enable file and print sharing, it's still inaccessible.
Why not learn how to install, configure and maintain a firewall?
I have a PC at work whose C$ drive has to be remotely accessed.I have administrative privileges in the system but can access the drive using the credentials remotely.
I can do the Remote Desktop Connection but not without logging off from the system.
I don't want to share the drive over the network which might cause security problems in the future.