It has 142,000 miles on it is that good miles for this type of car? Also is it possible to buy a new engine or whatever and I go all the way down to 0 miles and start fresh? I am only 17 and dont know jack about cars that well.

For that year, that mileage doesn't sound bad, I mean, I have an 02 with 198,000 already on it, but I'm the one that put those miles on it. Based on the math, that car has been driven approx. 9,500 miles per year, which is pretty damn good. As far as resetting to "0" after installing a new engine, you might want to replace the transmission as well, or else the tranny will still be "old". Good luck with whatever you decide to do.