First let me say .....Welcome to HE..LL......I agree grounding by its self doesnt work.If they are really really head strong talking wont do much good either..(they are not above telling you what you want to hear).atleast not at first.My oldest could sit in her room for years(it seemed) no phone no computer and no TV....I would let her watch tv with me after a few days.It would be a week before she would do that...but when she came out after a while we could talk a little bit ....Part of being a teenager is finding your self (some of us still are)....what lil bit Ive learned is about all ya can do is stick to your guns...and try to keep them on the road and out of the ditches.
I think we as adults sometimes forget what its like to be young again...alot more peer pressure these days...
Also one thimg that used to help with getting them to talk is eaitng supper at the table togather...we dont do it much anymore but you can find out some of what there doing and sometimes alot about what their friends are doing .....and piece some of it togather.
And sometimes no matter what you say or due they still get off track and have to learn the hard way..
GOOD LUCK