how do i reset my htc desire 510 when factory/hard reset buttons wont work and i dont have my password? I have tried holding volume down and power multiple times, i can't access the boot menu.  I tried accessing it every way possible with no success. I cant get into the phone to reset because I don't remember the password. How can i reset the phone or get into it somehow?
When your phone starts and you connect it to your PC you can restart your phone into bootloader using adb (USB-Debugging has to be enabled). 


Connect device to PC and be sure that the drivers are installed
Download the Android-SDK (it includes adb) or find a stand alone on google
navigate to this folder and run adb devices
when your Device is shown your drivers are correctly installed, if not check this
Now run adb reboot-bootloader and you are done


If USB-Debugging is disabled you have to try it with the hardware buttons. Remember that you have to press (and hold) the volume-down-button first and then press (and hold) the power-button until the Android images appear. You can also try to remove the battery for a few minutes and try again, sometimes this helps