I've been married for 15 years, and now have 2 kids.... Things were bad for us for a time, especially after the 2nd kid was born... Wife didn't feel very sexy, and wasn't interested in sex at all.. However, like clapping, it needs both hands to work together. If you still love your wife, and she still loves you, then it is up to the both of you to work together to bring your relationship and your sex life back to the way it was before the kids were born.
We found that we needed to make the effort, to reserve some time regularly to spend with each other alone, without the kids, and to learn to enjoy each other's company again, like when we first met. My wife is very conservative when it comes to sex, and I've tried to broaden her horizons by introducing variety to our sex life. e.g. I bought her a vibrator that we use together, and she said it was one of my best buys!
We usually try to get away by ourselves and stay at a nice 5 star hotel for 1 or 2 nights about once a month or so. We would have a nice dinner, wine, drinks, then maybe go to a movie/show/play, then back to the hotel to enjoy each other's company. This has made all the difference in the world to our relationship.