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Did you make any change to your computer recently that may have caused this issue?
Does this issue occur in any program you try on the laptop?
Can you turn off your computer. Then turn it on, and right after the black screen with white text or the computer company logo disappears, press & release key F8 repeatedly until a menu appears, then you select Safe Mode (note: if there is no menu, then try the same steps again, but this time, press key F8 a bit earlier), then check if you can type in safe mode?
In Safe Mode, can you click Start->all programs->accessories->system tools->system restore and restore the computer to any date before this issue has occurred?
If needed, can you connect a USB keyboard to the laptop and see if you can type with the USB keyboard on the laptop?
Please let me know. Thank you.