Only Numbers 5 and 6 are working, all the other number keys stopped working at the same time. I have a Inspiron laptop with Vista. The numbers all work when using an external keyboard plugged in. There does not appear to be any sillage under the keys. I have turned num lock on and off, and have tried re booting. Nothing makes any difference. What to try next?
Looks like the keyboard is broken or the cable that connects the keyboard internally to the mainboard is loose.If you are OUT OF WARRANTY and and are brave enough download the manual, read the instructions how to get acces to the keyboard,open the system. and reseat the cable.Do not use any force - often you have to unlock such cables by moving a little plastic slider on the connector.
Before you do this: reboot your system and check if you can enter the BIOS by pressing the function key "F2" - You must (and often several times to have success) press F2 before the windows logo appears)
If you can successfully enter the BIOS by pressing F2 and F2 is not working within windows then you might simply have a softwareproblem (unlikely but possible)
You might ask a friend to help you to open the system - or let Dell fix it for you.
I am only familiar with my inspiron 1545 but I think "F2" is valid for all Dell systems otherwise check the manual