Why is my laptop SO slow?

So I recently received a used laptop and it is the Dynabook Toshiba brand (has over 50gb of free space out of 70ish) thats from Japan. The problem is that it is so slow. For example if I were to click the start button, the start wouls get highlighted and then it would freeze. Once it pops up, I would move the mouse to any folder and click on it. It would then freeze, not load, then load and then open. This happens to pretty much everything including the internet when opening a new window, clicking a link, etc. I have downloaded CCleaner and cleared unnecessary junk and removed unwanted programs. It is still slow though. Can someone tell me how to fix this? I am becoming quite exasperated. Would a complete reboot (restoring to factory settings) do the trick? If so, how would I do this as I do not have the disc that is needed to restart it? Please help!