My laptop keyboard suddenly stops working sometimes....?

It might be an automatic thing windows is doing to save power. Try going in your control panel's power settings and see if there's anything about turning the keyboard off to save power. If so, just set it to never turn off this device. Hope this helps.

Can you still move the mouse? If so, it might just be a bad keyboard driver, or the connection might be bad (if you can do it without dismantling the laptop, try taking it out and disconnecting and reconnecting the flat connector under the keyboard - look up a guide). Otherwise, it's probably just frozen. Go into Power Options, and set the laptop not to go to sleep automatically if it's plugged in. Under Advanced Settings, try setting it to never turn off the hard disk.

It might be a problem with your keyboard driver. If the problem is recent, maybe you can solve it by performing a system restore. Is your driver up-to-date?

If nothing works, you can always increase the time before your laptop locks (I think it's somewhere in Control Panel > Power Options).

Sounds like your keyboard is toast. By that I mean has burnt up and needs to be replaced or either you can hook up a new external USB keybord would be my first choice.

It seems someone spilled something on your laptop and you will be lucky if it's only the keyboard.

Laptop is stalling. Nothing you can really do IMO. Restart usually makes it better. Happens to the best of us.