Memory card showing message can't play

Hello,
When iam trying to copy the movies or songs in the memorycard it is copied but when iam trying to play it it is showing message can't play this.When i tried to delete the files by connecting to the computer it is showing the message as can't delete the files the Android software is for only in read-only option.When i have changed with another memory card it is working properly.Please suggest me how to solve this problem.