Trouble answering calls on Motorola G
First go to Settings -&gt; Apps -&gt; Disabled(Tab). If you can find Dialer or Phone please enable it and then check after restarting your phone.

If your Phone/Dialer app is not disabled then try these steps,


Settings -> Apps -> All(Tab) -> Dialer
Clear Cache and Clear Data
Disable it and restart phone and Re-enable the Dialer app.


If problem persists you can for emergency purpose attend calls using your motorola headset.