LG Cookie text an inbox problem!?

[joes-f]

I've had my Lg Cookie for 6 months and had no problems, but last week I got a text off a friend, but it came through 23 time in a few seconds and I had to take out my battery to stop it. I deleted all of them execpt one that I couldn't delete. The little envelope symbol has a small sim card (like) on top of it. I can open the text, but when i go back to my inbox it goes back to being marked as Unread. I still can't delete it and now when i open it i get sent multiple coppies of the last text I recieved.... Please Help