If you have a backup of your data, you can do a selective restore of the address book. Other than that, the contact is gone.
__________________ The difference between stupidity and genius is that genius has its limits. When you take things for granted, the things you are granted, get taken. Even a mosquito doesn't get a pat on the back until it starts to work. Too many people miss the silver lining because they're expecting gold. [BES 5.0.3 / GroupWise 2012 HP2]
I did this the first week I had my phone. I deleted one of my good friends number. I know I had stayed in touch with him so I just jumped on my website and looked at my SMS history. I had TMobile when I did this, and TMobile stores what SMS texts I sent.