My turning signals work when they want to. The left one does not work at all

You probably have some bad bulbs-replace all four for starters.The flasher unit may be bad s well.It's usually a plug in type of thing under the dash.

BOTH OF MY TURN SIGNALS WORKED INTERMITTENTLY. THE FIX WAS TO REPLACE THE "SECOND" SIGNAL FLASHER AT A COST OF $350.