My dog has become timid after 2 dog attacks and doesn't want to go walks anymore?

your best bet here would probably be getting professional advice and help from a behaviorist who specializes in this type of traumatic event. if you try anything on your own you may only make matters worse.

There is not much you can do about this but wait and allow time to make it better. This is a normal reaction. A friend of mine was walking his little westie and he was attacked by a neighbor's dog that had dug out of the fence. Poor little guy starts to cry when you reach the sidewalk in front of the house. I just told my friend to take him around the yard and forget about it. I think that having them be so stressed from the fear is very harmful and it must be a horrible feeling for them. I would not force my dog into that situation. He sees the situation as you have allowed this to happen twice and have not been able to protect him so he wants to run away as it is the only way he can try to avoid the terror. Just think about it from his point of view. I would just give him some time or be absolutely sure that his environment is safe. At this point, he will probably be fearful of any dog that runs up to him, even if they want to play. Poor guy. Good luck with helping him.

Poor guy.

I would seriously consider getting a behaviorist. Have a behaviorist or a trainer experienced with timid dogs come to your house and work with your dog. He/she may have some appropriately submissive/calm dogs they might want to use to help ease your dogs fear.

Do you have any friends who own submissive dogs? Meeting up with them so the dog can have positive interactions is a good way to get him more comfortable with coming across other dogs.