If you need to rename all folders and files to lowercase on a case-sensitive filesystem (e.g. ext4 on linux), you can use the following at the bash prompt:

If rename is available (if you have Perl installed, then it usually is):

find . -depth -exec rename 's/(.*)\/([^\/]*)/$1\/\L$2/' {} \;

If you can't use rename, try this:

for SRC in `find my_root_dir -depth`
do
    DST=`dirname "${SRC}"`/`basename "${SRC}" | tr '[A-Z]' '[a-z]'`
    if [ "${SRC}" != "${DST}" ]
    then
        [ ! -e "${DST}" ] && mv -T "${SRC}" "${DST}" || echo "${SRC} was not renamed"
    fi
done