I have three queries gives me result individually correct but my requirement is i need all result in single query only so how should i proceed?

select * from user_post_like
inner join user_post  on user_post_like.postID = user_post.postID
inner join Users on Users.userID=user_post_like.userID
where (user_post.poster='$uid' AND user_post_like.userID!='$uid')
ORDER BY likeID DESC;

select * from user_post_comment
inner join user_post  on user_post_comment.postID = user_post.postID
inner join Users on Users.userID=user_post_comment.commenter
where (user_post.poster='$uid' AND  user_post_comment.commenter!='$uid')
ORDER BY commentID DESC;

select * from user_post_share
inner join user_post  on user_post_share.postID = user_post.postID
inner join Users on Users.userID=user_post_share.Share_user_id
where (user_post.poster='$uid' AND   user_post_share.Share_user_id!='$uid')
ORDER BY shareID DESC;

Since you're joining the tables anyway, you can put columns from all in your select - and keep your statement readable. If you have duplicate column names (from different tables) you may need to aggregate them with functions and group by.

SELECT s.*, p.*, u.*
FROM user_post_share s
INNER JOIN user_post p ON s.postID = p.postID
INNER JOIN Users u ON u.userID = p.poster
WHERE (p.poster='$uid' AND s.Share_user_id != '$uid')
ORDER BY shareID DESC