I just got my blinker back to working condition. The parking lights worked, but the front left blinker did not.
Check these things:
Does the light illuminate for Parking Lights?
Does the light illuminate as a Blinker?
Does the light illuminate as a Hazard Light?
If the light works for a hazard light, but not for a blinker, it is your turn signal switch. If it works for neither, than it could be the bulb, or the wiring. If the bulb is fine (check it off the car), then test the light assembly. Most likely it is corrosion or your ground.
Mine had tons of corrosion which needed to be scraped off. I cleaned it all up (especially the GROUND on the back of the light assembly), then put it all back together with DIELECTRIC GREASE. It works now.
P.S. - I have a slightly used (< 2 years old) turn signal assembly (OEM Porsche) that works fine. I accidently replaced it troubleshooting something else. If you need it, I will sell it to you for cheap!!! E-mail me.