句意：如果不解决,这个问题可能导致更加困难的局面.
补充完整：
The problem may lead to a more difficult situation if it was left unsloved.
leave sth.+ adj.使.处于某种状态
状语从句中,如果从句主语和主句主语一致,从句中又有be动词,从句主语和be动词可以被省略.
例如
Look when crossing the street.(=Look when you are crossing the street)