I can't delete files 'rm: cannot remove X Read-only file system'

Solution 1:

Depending on the state of things, the output of mount may not reflect reality. You're far better of with cat /proc/mounts, which is guaranteed to show you the actual mount table, wherein you'll probably find that it's actually mounted read-only. You can fix this with mount -o remount,rw /mount/point. If that command errors out, then your filesystem is hosed in some way; a fsck (at the very least) is in order. You don't need to stop the entire system to fsck a partition, just that partition needs to be unmounted.

Solution 2:

You could try remounting the device and seeing where that leads

mount -o remount,rw /media/usbdisk

If that doesn't work then you'll probably need to fsck the device

umount /dev//media/usbdisk
fsck /dev/sdb1

You may need to use the -f option to umount for force it to be unmounted though.