Windows 7: How to default windows 7 keyboard setting?

Four weeks ago I changed my laptop, then I gave my old laptop to my family as a public laptop. But today I must use that laptop, so I found an issue. I can't type some key with shift key. When I hold shift key and press "-" key, or "=" key, there's no "_" and "+" key following. but I can't type "_" when press "-" after I put my finger of shift key.
It's really annoying. So I want to know how to default it or fix it. Anyone help me please?
Sorry for my bad English, and Advance thanks!

This is just a guess on my part, do you have sticky keys turned on?
Using StickyKeys - Microsoft Windows
Jerry

No, but when I do I still have this problem.

Check the Keyboard layout. It is probably set to English (United States) US. Perhaps it needs to be changes to your language?

Control Panel, Regional and Language, Keyboares and Languages tab.

My default language's English(US), and the layout is still look like the way it is. Here's a picture http://www.sevenforums.com/attachmen...1&d=1346327495 . What should I do next?

Maybe the keyboard is defective? Try connecting an external keyboard, see if that works.

No, I think. I can still type normally, but I must hold shift and hold a key, then remove holding shift again for typing it.

Check the Keyboard repeat settings in Control Panel / Keyboard.

Mine looks like this: