Space, Enter, Backspace and Print Screen keys do not work on Inspiron 14 5430

I bought this laptop a few months ago and recently the keys stated in the title above have on occasion stopped being responsive with increasing frequency. Attaching a USB keyboard does still work which is how I am typing this out and running both window both windows trouble shooter and dell support shows that there are no software issues detected. I am asking for any advice as to what can be done. Should worst come to worst I can probably still get it repaired or returned as it is still in warrantee. Thankyou In advance.