Cannot format sd card anyone else have this problem?

my droid was lagging so i shut it off and turned it back on. it kept saying preparing sd card checking for errors in the notification bar but it never finished. i took it off and tried to format it but was unable to complete. tried deleting 1 file at a time and there are files that are 0kb that even though i delete just keep reappearing. how can i format the sd card?