Recently, I have used Nexus 4 for testing my apps. It's really weird using Nexus 4 with Windows 8.1. I spent a lot of time finding how to work with MTP. The system was not installing MTP drivers. Well here is the below link that will tell you exactly how to do it.
You can also follow the quick steps below.
1. Download and Install USB driver from Google for your device.
2. Follow the steps provided in the above link for a successful driver installation.
3. After installations, go to device settings -> Go to Storage -> Select "USB computer Connection" from action bar (menu).
4. Check Media devices from the option.
5. Connect to your system.
The MTP installation should appear if not already done.
Whenever a major system update happens, it seems android resetting the settings sometime. So, please check for these settings if you update your OS in future.