how can i clear my cache?

I dunno either. But thanks for those who responded here. At least, i gain an idea. I will do clear my cache as well.

You can also use this useful utility named CCleaner which does all the job of clearing cache, cookies, history, unwanted files and form and passwords, etc. It is free to use and download and i use it every week to clear all these unwanted things on my computer. I would suggest the same to you also.