What is meant by Living God? Why is Lord Jesus the True Living God? I would like to know what is meant by Living God? Are there non-living Gods also? I don’t think so. I partially understand that Living means who is alive. But I don’t know the true meaning. Someone please clarify if you would know.
As @NigelJ commented, the term "Living God" was in common use in the Old Testament, and when Jesus came He was naturally called the "Son of the Living God".

As you indicated, "Living" means alive.  On the other hand, "Non-living God" is usually termed "false god" in the Bible, referring to a god that is a product of human imagination, a corruption of the true God Yahweh, resulting in idol worship.  The prophets seriously warned Israel not to worship those gods because instead of giving life, one of them (Molech) demands child sacrifice! The prophets were relatively silent as to whether there are real demons behind those "gods" but emphatically warned Israel NOT to worship those "gods" because it broke covenant with Yahweh, invited curse and punishment, resulting in death not life.  

When Jesus came, Jesus further revealed the true nature of Yahweh, so naturally the NT authors also gave Jesus the adjective "true" and encouraged the believers to beware of false teachers who propagated "false gospels" which corrupted the nature of Jesus and God in the NT period, and similarly broke the new covenant, invited punishment and resulted in death rather than life.

If we look at the range of uses in both OT and NT we can see within the context of those verses several reasons why the Biblical authors attached the adjective "Living":

In the OT:


As the God to be feared (Deuteronomy)
As the God who will win a battle for Israel (Joshua, 1 Samuel)
As the God who will punish foreign nations for their defiance against the God of Israel (2 Kings, Isaiah, Jeremiah)
As the God who can save us (Psalm, Daniel, Hosea)


In the NT:


As Jesus's identity (Matthew 16:16)
When demanding someone to swear most seriously (Matt 26:63)
When redirecting worship to the real God (Acts 14:15)
etc.


Here's a good article going over various verbs that God did as a Living God:  speaks, listens, takes initiative, reacts, saving, which then prompts us as believers to naturally want to serve Him.