If a key or keys were stuck I would expect a beep sound, and if the keys were stuck, then the keyboard would be functional.
You say you couldn't use your keyboard, and you were confronted with popups...perhaps your system has been compromised.
Have you scanned it for any malware yet (viruses, spyware & adware) ?
Also, have you made any significant changes to the system lately?
Anyways...glad it's working now, and about your keyboard, does it work, and do you see any keyboard status lights illuminate during POST (just when you power on your PC)? Check device manager and ensure that your keyboard has been detected, and that a keyboard driver has been installed.