If the hidden files are not shown , go to My computer > tools > folder options and in the resulting window, go to the view tab and select the Show hidden files and folders radio button.
If the hidden files are not still shown, it might be as a result of a virus attack, in such cases try the registry hack.
Open the registry editor.
Start > run > regedit.
Navigate the registry entry, HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL and then in the right pane, create a new DWORD entry named CheckedValue (note the spelling correctly) and then set its value to 1.
Restart your computer. If the hidden files are still not visible, then go back to this location and check the value whether it is still 1. If it is changed, then there is some kind of a virus in your computer changing the value, you must first delete the virus. A good free antivirus is Avira Antivir Free edition.