I can't delete files on my micro sdhc memory card?

I know how to format and how to delete files on a memory card but this time it isn't working. I tried to format it with FAT but after formatting an error comes up and says "Formatting is not Complete". I also tried to scan the memory card cause I thought it had a virus but it comes up clean. Whenever I access the card in Drive F my computer hangs a little bit(about 3-4 secs.) I have deleted some of the files but when I access the card again the files are still there. Help please :(