Dell inspiron 5100 single key does not work

[delllaptop]

Hello,

my comma key went kaput some time ago. Every other key works fine.

Where do I start?

 

[phyco126]

Gently, carefully remove the comma key. Press on the button that was underneath the key. Did it work? If so, then the key itself was damaged and can be generally replaced for a few dollars or so. If not, then the keyboard itself is likely damaged. That will cost considerably more to replace.