What is happening after building light?!

Before Building Light (production or preview it doesnt matters) first 2 pics, - After building light, last 2 pics Why its happening?

Re-Loading last 2 pics. (I only hit ‘’ Build lightning only ‘’ )

Do you have the importance volume, the skylight, and the post process volumes all in place?

for the first picture it seems your spotlight is gone.
for the second picture it’s just darker. Like if your eye attenuation is on?

Taking a step back - how familiar are you with UE4? My guess is you have a mismatch between Lighting Types and Model Settings. Are they static lights and static objects? Static and Stationary lights are baked (movable isn’t). Also check your light map resolution to see if it’s appropriate for the size of your model in the scene (the default 64 is too small a large or complex object).

I don’t know what is the importance volume and post process volume. Can you explain what are they does and how to use them ?

didn’t worked.

Oh my god. Just setted my quality of graphs.Looks better and solved a bit. Thanks.Now i can set my graph and solve problems.

For the light importance and post process volumes you need to watch some tutorials or reas the documentation. It’s all explained.