Keyboard gets locked up

I have a HP laptop and sometimes when I am working I accidentally hit some combination of keys that makes the keys stop working normally -- suddenly everything does something else, if that makes sense, like if I click in a Word doc instead of the cursor moving there I select the entire contents of the page. I hit another key and go to the desktop or save the file. So it's like I'm in some mode, maybe enabled some accessibility thing, but I cannot turn it off with any combination of keys (e.g., esc doesn't undo it, or ctrl+esc, or Windows+esc). I have to actually restart the PC sometimes just to use my keyboard again. I googled it but nothing is helpful (e.g. it says hold down the right shift key for 8 seconds, but that didn't do anything, nor did Ctrl+end, I don't have a numlock key or even the numlock label on any of the fn keys.). Any help and understanding what I'm acidentally doing and how to get out of it would be much appreciated. Not sure how to flair this, there isn't one for OS.