You might not have permission to

\\computer is not accessible. You might not have permission to use this network resource”[...]
9. Local Security Policy – Another reason you may not be able to access another computer across the network is because of a local security policy.
You can go to Control Panel, Administrative Tools, Local Security Policy, Local Policies, Security Options. Now find the following policy:

Network access: Do not allow anonymous enumeration of SAM accounts and shares

Make sure that the value is set to Disabled. Also, make sure to disable only the setting that says “SAM accounts and shares” not the one that says “SAM accounts” only.

10. Uninstall anti-virus and Internet Security