I chaged front brakes on my 2002 audi a4 tried to bleed, but pedals still soft. does anyone has a solution to this?

I've never worked on an Audi a4, but I am very familiar with brakes and hydralic systems. You can have a "soft" pedal for a number of reasons. The first and foremost is air in the lines, but that's not the only reason, but the usual one and it could be yours. You failed to mention how many miles you had this vehicle and if when you changed your brakes you had the rotors turned. Depending the shape they are in can be the problem or maybe part of the problem. The reason I asked how many miles you had is do to the fact at times when people change their brake pads they look at the rotors and say to themselves. "Well they don't look that bad", and yes they might not look that bad, but that doesn't mean they are not worn down past the point where they should be replaced because they are too thin. When your rotor gets thin it causes the pedal to travel more then it would if the rotors where new and since the pistons in the caliper are traveling a greater distance it can make your pedal feel "soft".
It also could be coming from your rear brakes. I assume that they are shoes instead of pads, and when they get worn down they travel further. The distance is multiplied when the drum has been worn down smaller also.
Now another part of the equasion is you master cylinder, depending on the miles again it could be the problem or maybe part of it.
Another thing it could be is the metering valve.
With all of this said, I would adjust the rear brakes out as far as needed and then re-bleed your system. Start with the wheel that is the furtherst away from the master cylinder working to the shortest distance from the master cylinder.
Now get this. I had a friend who told me once (and I still don't know if I believe him) That after awhile your brake fluid can loose it compressionability, (thus causing a soft pedal) and it needs to be changed when it starts to look dark. He said the reason it gets dark is basically for 2 reasons. One, it gets too hot and burnt over the years of use and it get's dark fron the seals that are starting to deterioate. I don't know about that, but it kind of makes sense.

When you change out the front brakes you dont have to bleed the system you can use a C clamp to close the caliper or a brake tool that is made for that purpose.If your brakes where soft before the brake job its usually the master cylinder that is loosing pressure.But if you losened the brake line to release pressure and close the caliper most likely you got air in your system.You must bleed the system if you got someone to help you if not they have vacum pumps to get the air out.Good Luck