Could someone please help me.My dog eats every piece of food she can get her hands on and still wants more.Why? Is there anything I can do to stop this?

How big is the dog, how often do you feed, how much do you feed? Many dogs will eat until they get sick. Dogs do not "think" in long ranch and think every meal may be their last portion, eating all you can when you can.

Is this something new or has she always been this way?
Are her bowel movements normal?
Is she losing or gaining weight? What about her water intake is that also in excess?
A little more history would be very helpful.

My dad passed away and I inherited her. She weighs 19lbs. She does like to drink as well. Had her to the vet today. All tests came out great except she has an infection from having dirty teeth. Had them cleaned and now she is on antibiotic. I also have a ****zpoo and he never acts like her. Could she have maybe been starved at one time or had to beg for her food. She is 12 years old can I untrain her from feeling like she is starved?

Good for you, for having her teeth cleaned and having some testing done.
The dental cleaning will no doubt be very beneficial for her health wise.
Some dogs, I feel, will seem starved all the time, and would eat all day if you let them.
I've had a couple of parvo survivors that act as if they are constantly hungry.
My theory is that the time they spent unable to eat plays a role in this.
Not that you do this, but free feed is never a good idea, especially for these dogs, controlled times and portions are best.
A food that is a little higher in fiber may be beneficial, since your vet has a good understanding of her general health they might could suggest one.
You could also try treats like string beans added to her regular meal. Carrots, and sweet potato are also good for increasing fiber, this should help to make her feel fuller and more satisfied.
Of course remember that increasing fiber will affect her bowel movements, so you will want to make sure she has the opportunity to go out more often is she needs to.

I have a 10 yr old Standard Dachshund who has the same problem. He has always had a fantastic appetite and even though he was on expensive scientific dry kibble specially formulated for weight loss he just seemed to put on more weight. Finally a few months ago he developed a terrible skin condition and we took him to a new vet who took him off all dry food, and I have to cook for him for 2 months ( 2/3 veg to 1/3 meat). Living in Australia one of the best meats for him is kangaroo, goat, lamb, turkey and pork. No chicken or beef at all, no processed food or treats, no pasta, rice, etc. The best veg are the gold or orange sweet potato, pumpkin, carrot and any other veg that the dog will eat. Through trial and error I have come up with kangaroo mince, sweet potato, pumpkin or butternut pumpkin and carrot boiled together with a little salt. He gets about 1/3 cup in the morning and again in the evening (but being the fussy boy he is, it has to be warmed). After 3 weeks on the diet, he has lost weight, his coat is stunning, the skin problems are all gone and he is suddenly full of life again, playing with the 5 yr old dachshund like he did when she was a puppy. The first few days were very hard, he is very demanding, but he quickly learnt that there were no treats coming his way and neither was he going to get more food. They are very clever! Good luck, well worth it in the end.