How to unlock core for my CPU

Howdy!

I'm still new here, as well as to the OCing world. I'm not very familiar with computer hardware advanced terms, although I'm a Computer Science student, so I might have trouble wording exactly what I'm looking for.

Anyway, my desktop is an old Compaq Presario QC5600Y that I bought 2 years ago. I tried upgrading few parts so I got a 1GB Video Card that was top at the time, and I maxed its ram to 4GB.

The CPU is a AMD Athlon ii 170u, and I could swear that when I first got the computer, the task manager would show me that it has 2 cores. But now it shows only 1 for some reason.
I tried following some tutorials online that show how to unlock the second core via BIOS, but it wouldn't even give me access to the advanced clocking options.

But is it even possible to overclock / unlock a core on that old thing ? or am I just wasting my time ?
And if it is possible, how can I do it, please?

I'm willing to provide any needed information if you could please help me.

Thank you
OctaHex

According to this it only has one core: http://www.cpu-world.com/CPUs/K10/AMD-Athlon II 170u - AD170UEAK13GM.html

Some CPUs come from the factory with locked cores that can be unlocked, however, and are marketed as something with fewer cores than are physically there. In order to unlock the locked cores (if there are any) you would need a motherboard bios that had tools to unlock cores. I seriously doubt that any box store Compaq would have a bios that allowed you to do that or to overclock the components. The mass market computer manufacturers just don't want you altering stuff.

In the case that somewhere in the bios there is an ACC option, enable it and it should unlock the second core.