Missing Reg key for "show hidden files folders"

There was some hackittoolkit zip file in my system running windows vista and it was reported as threat by my antivirus program. My antivirus has removed it but since then "show hidden Files & Folders" is missing in my case. It was there until hackittoolkit was in my system. I want to know if i can add that missing option back again. I have chatted about this with some of my friends and they said that my windows registry might have got messed up and i will have to edit it. I don't have any idea about the registry and i haven't tried editing the registry yet, so is there anyone who can help me out???

I will suggest you to run "sfc /scannow" command, you can refer to below steps for running sfc /scannow command:

• Go to start, click on run, type "cmd" and hit enter
• Once you get the command prompt opened , type "sfc /scannow" without quotes and hit enter

A small scanning process will get started which will fix missing or corrupted system files on Windows Vista or on Windows 7.

Yes your registry might have got messed up, In order to fix it try below steps:
Go to start > click on Run > Type "regedit" without quotes and hit enter
In new windows navigate to [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced] "Hidden"=dword:00000002 and change its value from 1 to 2.

Give it a try and post back if it helps.