Muffled thumping noise on driver's side wheel area

Could be something really simple. I would start with turning the wheel all the way to the left and checking the tire for nails/screws/rocks stuck in the tread. Also look for strange bumps in the tread or sidewall. Then turn the wheel the other way and do it again. Straighten it out and move the car forward a foot or so, and then repeat the check. Also, while you are down there, make sure that the lug nuts are tight.

If you find a nail or anything in the tread, take the tire to a small mechanics shop or tire place and get it patched. That should not cost more than $10.00 or $15.00.

Good luck and let us know how it goes.

Does the noise change if you turn the wheel back and forth? You say it stops if you turn right, does it come back once you complete the turn?
You say it is louder when you use the brakes? Do you actually feel a vibration that is in time with the thump when you use the brakes?
If so you could have a broken brake rotor. I have seen them crack in a straight line and cause a strange noise.
It could also be a bad wheel bearing allowing the wheel to shift. Hard to say for sure without hearing it ourselves.

I would start by jacking up the front end and see if you can move the tire/wheel in/out at the top or in any direction but rolling. Any play will show a problem, check both sides ad sound can travel and cause you to "hear" it in the wrong place. Also check the rears for the same reason.

I am with Steve. The next step would be to jack up the car and start visually checking for bearing problems, loose bolts, and problems with the brake system (like a broken rotor, loose caliper, etc). Let us know.