Always buy the two parts together even if it looks okay cause if your phone isn't displaying anything, it means the LCD display broke. And naturally if you drop your phone the glass has to take damage and you'll have to buy a new glass anyways.
It's either you didn't connect the digitalizer to the phone's system panel properly, or the digitalizer you bought is not working. Buy another one... Not recommending from China because that's one of the risks of buying from there: defective items.
Try to stick to whatever's close to you. It wouldn't be nice if the laptop arrived broken and you having to spend money on it without guarantee that it'll fix, that's not convenient