More than likely the Flasher Relay is bad. If the bulbs are lit but will not flash it is definitely the Relay. This can also indicate a bad bulb on one of the lights on the side that does not flash.
Sounds like a weak turn signal flasher
It looks like your left front one is burnt out. When there is not enough current flow the good light will not flash.
Could be a burnt out bulb or a bad flasher unit.
More than likely the Flasher Relay is bad.
Sounds like you need a new flasher.
under the steering wheel you have to take the how thing apart and its a round thing p.s. its connected to the turn signal lever
a bulb is out
You may need a new flasher.
Check your bulbs, most of the time if you have a bad bulb, the side with the bad bulb will stay lit, and not flash, but the other will work fine, your hazards should work, unless you drive a 72 nova
Be sure the 4-way is turned off.
You could be hitting the flash feature on the turn signal arm when you use it.
Depending on year of vehicle - may have a separate turn signal flasher that may be defective