What sort of given up...? Sometimes a heavy blast out with GT-85 or similar can renew a gunked up shifter, along with a brand new cable (inner and outer).
Try using a hair dryer in the shifter too Soften the grease which has Harden then add a bit off wd40 and keep Operating the shifter at the same time should free it up.
What sort of given up...? Sometimes a heavy blast out with GT-85 or similar can renew a gunked up shifter, along with a brand new cable (inner and outer).
If it's snapped/ruined etc, then as you were