I have a Toshiba laptop [A105-S4084]. But i am not able to use the laptop since the keyboard behaves as though the ALT key has been pressed, When I go to the Virtual Keyboard, I can see that the ALT key has been pressed. It does not work with a external keyboard. I have even removed the ALT keys from the laptop keyboard, but still it does not work. I tried formatting and reinstalling the OS as well. A friend of mine suggested it could be a problem with a motherboard. Please let me know what could be the cause of the keybard issue and if the motherboard could be the reason behind the faulty keyboard.
It could be bad keyboard. They don't cost too much...roughly $25-$30. They are not that hard to replace. I am amazed that you were able to get the alt keys put back on; Those things were usually very hard to put back on on some laptops, if not impossible.
What you could also try is to reseat the cable that connects the keyboard to the motherboard.