Lock button broken?

[quinlisk]

So I recently updated to 5.0 and about a week after my lock button started to not work every once and awhile and now the button has stopped working all together. Idk if the software update is related to my problem or not. My warranty is up so Im kinda on my own. Any suggestions on how to fix this? And if its the button itself can anyone lead me to a link of what I need to buy to do the replacement myself. Any help will be greatly appreciated.