Recently I saw my Task manager window and was surprised to see that there were only 3 cores ! To make it sure I installed CPU-Z and even that showed I had core2Quad Q6600 with 3 cores , I dont know what to do and have never even tried to change my BIOS settings. I have posted a CPU-z Image showing my cpu results.
If anyone knows how to bring my missing core back than please help me

If anyone knows how to bring my missing core back than please help me