Why your 99 gmc surburban wont start but will turn over?

Bad ground, bad battery, harness or bad connection. Not enough info here, need to know if headlights come on and if you even get a click. Does it start with a jump?? In this order check bat( should be 12.3 V or above check and clean terminals check connection to ground check connection to starter(unlikely since you replaced it.) email me @malq@comcast.net after you try these Doug