how can i unlock a DVDR cd with data on it?

[a j h]

i think i messed up and screwed up my back up cd with my pics and things on it. what happened was i was adding more stuff on it and then i needed to take it out because i needed that drive to do something else and so i did. and now it won't show any of the stuff on it and says i can't see it because it is locked to my computer. please help.