I made a great mistake that I selected all addons in blender Without knowing the uses of that add-ons. Now I'm confusing all are looking like new. Some tabs are new. For that I unseleced all add-ons now I don't have cycles render and many useful options. Please help me to reset all add-ons which presented when I open first 😥

Try resetting Blender with "Factory Reset".This would reset Blender to its initial installed state and hopefully also activate the uninstalled addons.
Note other settings like user defined hotkeys would be lost if this approach is followed.

• Thank you, wow I didn't see that factory reset. Thanks it worked – Alex Matt Aug 15 '20 at 15:15
• Should make the OP aware that this does not automatically save new startup file if they saved addon prefs beforehand (this is a new default feature in 2.8).. See docs for more info. In other words, this is a temporary fix unless new prefs are saved. – Timaroberts Aug 15 '20 at 15:43

Test script Disables all non-default addons (not listed as default) and saves user preferences.

import bpy

"io_curve_svg",
"io_mesh_ply",
"io_mesh_stl",
"io_mesh_uv_layout",
"io_scene_fbx",
"io_scene_gltf2",
"io_scene_obj",
"io_scene_x3d",
"cycles"}

# enable defaults