Do you mean the left shift lever between your legs? or the shift lever to the left of the steering wheel on the dash? If it is the left lever between your legs/ you will need to remove a snap ring securing the lever that is under the rubber boot. Pull the shift lever out and then reach down into the hole with a long screwdriver to align the 2 shift rails into neutral. Then reinstall the lever and all should work again. If it keeps getting jammed, then one or both of the internal shift rails may need to be replaced.
