My fallout new vegas dlc won't work, i've tried deleting it and reloading it and it still doesn't work, how do?

I recently downloaded a patch on New vegas and when i checked to see if the new dlc i had downloaded was there it was gone, along with all of my other dlc, i tried deleting it from my system and reloading it and it still didn't work. I've spent like twenty to thirty some dollars on this stuff and i'd really like to be able to play it! Help?