After too many failed attempts, your EVO will become locked. At that point it will ask you to put in your gmail username and password. If you dont know your gmail username and or password, you may have to reset your device. another option is if you have sent any email to any of your friends you can always have them let you know what your gmail address is and you can try to reset your password: here is the link to go to to reset your gmail password:
If you dont know the gmail username and or password, here are the steps to reset your device:
Please note that all data will be deleted from the HTC EVO 4G as a result of this procedure. This process does NOT delete data stored on the microSD card. We recommend backing up all of your personal data before proceeding.
If you selected YES, all data including third-party applications will be deleted from the HTC EVO 4G. Once the wipe is complete, the phone will reboot to its factory fresh state.