Dinc Dead.

you will need to hard reset the phone. you will lose all data, but your phone will be back.

With the phone turned off, press and hold the VOLUME DOWN button, and then briefly press the POWER button.
Wait for the screen with the 3 Android images to appear, and then release the VOLUME DOWN button.
Press VOLUME DOWN to select CLEAR STORAGE, and then press POWER.
When asked to confirm, press VOLUME UP.
 
You may want to just try a battery pull if you haven't ... normally I dont suggest that but it's less drastic than what marcw suggests. If not then do his suggestion.
 
My phone is stuck on the white htc screen????

Another big help in helping people help you (man that's a lot of helps) would be to let us know what you were doing right before you had this issue. Different problems sometimes come to a different conclusion for a fix.