[CmZxC]

pawn Code:

if(positionx[playerid] != 0 && positiony[playerid] !=0 && positionz[playerid] != 0); {
SetPlayerPos(playerid, 1676.8462, 1447.7908, 10.7833);
}
else {
SetPlayerPos(playerid,positionx,positiony,position z);
}

maybe switch != 0 into == 0..
you check if its not 0 then you spawn him at your default spawn.

AND you have to add

pawn Code:

positionx = dini_Int(Pos(playerid), "PositionX");
positiony = dini_Int(Pos(playerid), "PositionY");
positionz = dini_Int(Pos(playerid), "PositionZ");

at the spawn too.

so result :

pawn Code:

public OnPlayerSpawn(playerid)
{
        positionx = dini_Int(Pos(playerid), "PositionX");
        positiony = dini_Int(Pos(playerid), "PositionY");
        positionz = dini_Int(Pos(playerid), "PositionZ");
        if(positionx[playerid] != 0 && positiony[playerid] !=0 && positionz[playerid] != 0); 
        {
                SetPlayerPos(playerid,positionx,positiony,position z);
        }
        else 
        {
                SetPlayerPos(playerid, 1676.8462, 1447.7908, 10.7833);
        }
        return 1;
}