Try a USB external keyboard. If it works fine then you can assume the laptop keyboard is defective. Also run diagnostics, F12 at boot, and watch for errors but more than likely the keyboard will need replacing.
Hi, the keys 1qaz of my Inspiron 7590 stopped working all at once. I tried everything (tutorials, DELL repair tools, re installing the system) but no way to find out  solution. before sending it to repair I am asking support here. Thanks for any advice you may give to me
keys 1qaz stopped working