I read the USB is fine so the question is about a new laptop keyboard.
https://www.google.com/search?q=replace+n5010+laptop+keyboard&ie=utf-8&oe=utf-8 finds videos.
Maybe 20 bucks? https://www.amazon.com/Dell-Inspiron-Laptop-Keyboard-09GT99/dp/B005ES720E See if you think that's it and decide if it's worth the gamble.
My Dell N5010 has a partial keyboard problem. Most letters do not work, numbers & function keys are OK. A new keyboard did not fix this. A USB keyboard and mouse works fine. Processor is an i3 with 8mb ram, runs windows 10. Any clues anyone?