Shelia did u unmount the card before removing your sd card if u didnt an it had stuff on it: there could be a possibility of it not wanting read ur card when u pute it back in the X or may ruined the card were it won't work at all an like G said a trip to Verizon: But for a ( new) card may be instore an the cost for a new sd card is $49.99.
one thing i like to suggest : to shelia and others reading this i no its so exciting when u get ur new phone an u want to play with it as soon as a u get the programming done at the store or if u get it online To see what this does or that does but as excititing as it is please read ur manual Cover to cover an there are several ways u can get a manual as for the one that comes in the box when u get ur phone i wont commit on here what i think about that thing!. U can also read the post on here or just ask one of us before u do some thing to your Device u wished u haddent and we'll help ya as much as we can. We may sound alittle harsh at times but would'nt You rather have us tell u that than have your new Phone Down and not be able to do anything with it! but after reading ur manual an listning to us Go an have funnnnnnn with it OKie Dokie!