Why isn't my phone charging?

[AC Question]

I plug it and it detects the cable but it doesn't charge. Actually the battery drains normally
What should i do? I need help

 

[NerdgrlApps]

It's either could be broken USB cable - once I thought it was ok because I could transmit files between PC and phone, but I couldn't charge my phone with it though. Or something with the battery. Try to change the cable first)