How to access "stored user names and passwords" with rundll32.exe ?

The Stored User Names and Passwords applet lets you assign user names and passwords to use when needing to authenticate yourself to services in domains other than the one you are currently logged into. Here is a way to launch it using a desktop shortcut using the rundll32.exe program:

RUN> rundll32.exe keymgr.dll,KRShowKeyMgr

Show Hidden Files and Folders not working?

This issue might be due to some virus attack after which the
registry was not being updated properly.
There are so many methods to restore the registry.
Just try any of these solutions,

Sol 1:

Go to registry editor
RUN>regedit
Go to this key:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\Advanced

In right side of window, double click hidden and change the value to "1"
Now check the status!

Sol 2:

Run>regedit
Find the key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\SHOWALL
Check whether the “CheckedValue” is a DWORD key or not. Delete that key if it is not a DWORD key and create a new key called “CheckedValue” as a DWORD (hexadeci) with value 1
Now check the status!