^^ Detach the cable. The derailleur will return to the position where it's limited by the lower limit screw. Now turn the limit screw. See the derailure move? If no, check the screws / threads for damage, i.e. threading.
Photo would help.
@Howard started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
^^ Detach the cable. The derailleur will return to the position where it's limited by the lower limit screw. Now turn the limit screw. See the derailure move? If no, check the screws / threads for damage, i.e. threading.
Photo would help.