That is odd that you are getting a PUK code error on the HTC EVO 4G. You will normally get this code when you have a SIM card, and the HTC EVO 4G does not have a SIM card. Are you able to use the phone such as make calls, text, etc?
For immediate assistance you need to use the CHAT feature on the website. The CHAT link does not show up when you are in Communities or Forums - Go to the top of the page click on My Sprint>>My Account Wait for about 45 seconds and you should see the CHAT button appear next to your login name. If it doesn’t appear click on See My Bill and wait a few seconds. Click on the CHAT button for someone to verify your account information and gain access to your account. You can also dial *2 from your handset. On the forums we have no access to your account.