Use your brain Harjun.
What are you working on?...
...A PC (Well, Laptop) so you will find the paste in a...you guessed it a PC SHOP!
It means buying it though. If you listened to everyone then you wouldnt have to spend £7 on thermal paste. Nor would you (or your parents) be spending money replacing your laptop.
You parents will not buy you a One Thousand pound PC for doing well in Key Stage 3. Even if they do, please don't over clock that either. Overclocking may come across as cool and it does, a kind of geeky cool, even I want to overclock, but I have the brains, comon sense and knowledge to know better. There are about 15 pages of people telling you not to do it. Now we are only on our 2nd page of how to fix your problem, which everyone warned you would happen.
Please, tell your parents you were a little silly with your laptop, get them to take it to a PC Repair Store (as your nor your parents seem to have any idea on what they are doing) get him to right your wrongs. Forget overclocking, study hard, get a job, pay for your own PC and dont kill that one. Please Harjun, I'm being deadly serious, I want to sit back and laugh at you like I've never laughed at someone before, because...well, you deserve it. People have tried to help you before and because people here are so kind, they will keep on trying. But please, atleast know what you are doing and that WONT come with reading a few links. It comes with years of built up knowledge.
Just listen to what everyone is telling you.