1)Go to Start|Run
2)type regedit
3)Go to the path given below
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
4)There you will find
CheckedValue REG_DWORD 0x00000001(2)
DefaultValue REG_DWORD 0x00000002(2)
5)Change CheckedValue value from 2 to 1
i.e.CheckedValue REG_DWORD 0x00000001(1)
It will work.
3)Go to the path given below
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
4)There you will find
CheckedValue REG_DWORD 0x00000001(2)
DefaultValue REG_DWORD 0x00000002(2)
5)Change CheckedValue value from 2 to 1
i.e.CheckedValue REG_DWORD 0x00000001(1)
It will work.