how to flatten and tighten abs quickly?

You should go back to hip hop abs or maybe try another beach body program. Insanity is particularly good for the abs. Remember to pull your belly button in towards your stomach when exercising, especially during ab work. The vacuum is a good exercise for your transverse abdominus, which helps hold the belly in, it's basically sucking in the abs while pushing out the air from your chest and holding for 20+ secs:

http://www.bodybuilding.com/fun/ms-fit5.htm

And of course you have to lose fat to expose your abs, but a lot of belly pouch is from weak abdominal muscles and poor digestion

Yes you're right. I'm actually not fat. I can walk around in a bikini and not look like a total slob. But I just want to tighten my abs. Even though I've never had a sexy six pack, my abs used to be ok. But since I had a baby 3 yrs ago, I can't seem to get my abs back from the stretching they went through. If I'm crawing around on the floor cleaning or playing with my daughter, if I spot my abs they are hanging away from my body in a vertical line from chest to pelvis. It's not exactly sexy. I think my problem is mostly weak muscles and poor tone.

I think my problem is mostly weak muscles and poor tone.

You cold also have torn abdominal muscles from your pregnancy... not just a matter of them being stretched.

So if that's the case, what do I do?