With a microUSB connector, the first place I'd look (if I had your phone to repair - this is not a do it yourself project) would be the microUSB connector. One of the power pins (there are two for power, two for connecting to a PC) is unsoldered, and just close enough to the hole that, as you push the connector in, it makes contact for a moment. (Don't wiggle it around to check - the little sparks you cause can destroy that tiny portion of the motherboard, requiring a whole motherboard replacement.)
Bring it into a repair shop.
I assume that you've already tried another charger and another cable. (They're interchangeable - if a friend has a charger with a microUSB connector [not a Type C connector, which is oval, it doesn't have one side larger than the other], try it. If it works, it's your cable or your charger. Use your cable and his charger. If it works, it's your charger, if it doesn't, use his cable and your charger - that will work, you just need a new charging cable.)