passenger seat broken

Hello, I'd just call it a seat adjustment lever. This lever attaches to then seat and seat track. There's either something restricting the seat track preventing seat movement, or the release could be a concern. This will require some investigation including possibly removing the seat to inspect the track and frame and release mechanism. Once investigated it can either be released or repaired, or parts may be required -- impossible to know without hands on inspection. www.repairpal.com/repair-shops