Q: itunes wont recognize my iphone 6, even though it has previously

I plugged my iphone 6 into my computer, which then my intunes recognized the device. i tried syncing photos onto my phone and realized they were the wrong ones (after I disconnected it). Then, later on, try to plug my phone back into my computer just like the way before, and now itunes wont recognize I have my phone connected. also, cannot delete photos from my phone if they were synced from itunes