I cant get a hold of 2 owners of vacant houses and was thinking of mailing them but live in a apartment. what are the chance of them responding?tried calling them no luck. I think its also vacant over grown grass just messy but blinds are shut.
The chances of them responding is 50/50. Hows that for an answer? 
there is really no way of saying, just try to contact them in any way you can. Not every house you will find will turn into a deal but you will never know which will have that thick paycheck attached to it.
I don’t follow.
Who lives in an apartment? And what does that have to do with the price of eggs?
When you say you’ve tried to call, but “no luck,” what does that mean? No answer? You left a message but no one calls back? What?
And what is it that you “think” is “also vacant?” I thought the houses were known to be vacant, so are you talking about the apartment?
If you have a guaranteed address for them and you really think there are good deals to be had here, send them a Priority letter or even a FedEx. Have you ever known someone who didn’t open a FedEx?
Also, and I do not at all mean this disrespectfully, but if writing is not your strong suit, then before you do any direct mail, be sure to have the whole thing proofread by someone who his handy with the written word. You can even post your letter here and get lots of good (and free) feedback.