Around 45c is just fine.
Remove the old TIM and apply a fresh layer of good TIM like CM Thermal Fusion 400.
Can you please give me a online link to buy it as I am not able to find it anywhere online...
What I found is this. Pls tell if it is same.
New Cooler Master Thermal Paste Compound for CPU & Chipsets | eBay
Lastly I am still having the Thermal paste which I had got with the processor when I had purchased it. Will it work?
Yeah it should work but I am not sure about the quality of the TIM which is by default provided by CPU. Anyways you don't need to change the TIM right now, temps are quite alright. Change it when you get high temps, as a good quality TIM helps to lower the temps.