Forgetting your phone's password is a common issue faced by many users. If you have forgotten the password to your HTC EVO 4G Sprint, there are a few steps you can take to unlock it:

1. Try the default password: In some cases, the default password for HTC EVO 4G Sprint devices is either '0000' or '1234'. Try entering these passwords to see if they work.
2. Use Google Account: If you have linked a Google account to your device, you can try entering the wrong password multiple times until you see the option to unlock using your Google account credentials.
3. Perform a factory reset: If the above steps do not work, you can perform a factory reset on your HTC EVO 4G Sprint. Keep in mind that this will erase all data on your device, so make sure to back up your data beforehand.
4. Contact HTC Support: If none of the above methods work, it's best to contact HTC Support for further assistance in unlocking your device.

It's important to regularly backup your data and set up alternative unlock methods such as fingerprint or facial recognition to avoid being locked out of your device in the future.