This may not help you with your predicament right now, but...
Starting now you should G+ or Dropbox to keep your photos backed up. You can set Google+ to only upload while charging (i.e overnight if you plug it while you sleep) and to only use Wi-Fi, if you don't have unlimited data.
For now I would try a reboot of the phone and see if it helps. If not, pull the card and see if you can still see the pictures on the computer. If all else fails, download
Recuva to see if you can save any of the missing/deleted/erased files.