My HTC desire C says 'type password to decrypt storage' and I can't remember my password I got a new phone and am trying to sell my old HTC desire C with beats audio. When I turn it on it says 'type password to decrypt storage' but I can't remember my password, any way I can overcome this? It has no SIM card either.
Try this:


  Power off your device and wait for 5-10 seconds until the device is
  fully switched off. Press and hold Volume Down button, then press the
  Power button to switch on your phone and release it, but keep holding
  the Volume Down button. └ This will boot your HTC Desire C into
  bootloader mode You’ll see a screen with option to boot into Recovery
  mode among several other options. Here, press Volume down once to
  navigate to RECOVERY, then press Power button to select it and boot
  into Recovery mode. └ In Bootloader and Recovery mode, use Volume
  buttons to navigate Up and Down between options and use Power button
  to select an option.


Credit: http://www.theandroidsoul.com/boot-htc-desire-c-recovery-mode-52061/

You should have an option to wipe device. Unfortunately, if you forget your password, all of your data is just gibberish.