Why laptop won't connect to Huawei U3900 mobile phone

Hi Julie.
not sure if this link will help you out but have a look.
Huawei u3900 battery not charging Google Search

What do you need to transfer?
You can use android transfer app, which allows you to save a lot of time to transfer or backup text messages, contacts, photos, and other media files like videos, music files.
With the help of those backup tools, you can easily transfer files from android to computer.

MobiKin Assistant for Android Windows Version

How to Transfer Photos Between Android Phone and Computer

Try to connect the phone to the laptop using the phone USB cable, once connected make sure the phone is connected as storage device, it will appear in "my computer" as a computer drive, browse to the music folder and copy the desired music in it, after that restart the phone, Android will scan for media files at each restart.

You need to change mode from charging mode to camera or file mode. A message should pop up when you plug your phone into your laptop.

I figured this out. You need to add a memory card (SD micro) to the phone. Then internally move the photo files from the camera's internal memory to the SD card (done through the gallery menus). Once you have them moved to the SD card, plug the phone into your PC and it will recognize the SD card in the phone as an external drive. From there its easy. :)

Sometimes this means the phone is not connected to a mobile data network or a WIFI.

Check if your phone is connected to your vendor mobile service and try your gmail account credentials.

NCK code Or Network Unlock code all are same Only.You can get the Huawei U7510 Model NCK code from here
Theunlockspot.com
and get the Unlocking instructions there or follow it below and Unlock it step by step..


Huawei U7510 Unlocking Instructions Warning : Do not enter any wrong unlock codes on your Huawei U7510 mobile phones. If you enter over a certain amount of wrong unlock codes on your Huawei U7510 mobile phone, your phone may get hard locked and sometimes become unusable.
If your Huawei Device is a mobile phone:

1.Switch on your Huawei Phone using another networks SIM card.
2.Your phone should ask for an unlock code(NCK Code).
3. Enter the unlock code we sent you.

chek whther those driver supports vista?othwise try to find out vista drivers from site.....and even try manual connection through network connection...