Have you tried to activate and deactivate the plugin?
If it will not help run the following queries in your DB:
CREATE TABLE IF NOT EXISTS wp_likebtn_item (ID` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
identifier text NOT NULL,
identifier_hash varchar(32) NOT NULL,
url text,
title text,
description text,
image text,
likes int(11) NOT NULL DEFAULT ‘0’,
dislikes int(11) NOT NULL DEFAULT ‘0’,
likes_minus_dislikes int(11) NOT NULL DEFAULT ‘0’,
PRIMARY KEY (ID),
UNIQUE KEY identifier_hash (identifier_hash),
KEY title (title(1)),
KEY likes (likes),
KEY dislikes (dislikes),
KEY likes_minus_dislikes (likes_minus_dislikes),
KEY identifier (identifier(1))
);
CREATE TABLE IF NOT EXISTS wp_likebtn_vote (
ID bigint(20) unsigned NOT NULL AUTO_INCREMENT,
identifier text NOT NULL,
identifier_hash varchar(32) NOT NULL,
client_identifier varchar(32) NOT NULL,
type tinyint(1) NOT NULL,
user_id bigint(20) DEFAULT 0,
ip varchar(40) NOT NULL,
lat float(10, 6) NULL,
lng float(10, 6) NULL,
created_at datetime NOT NULL,
PRIMARY KEY (ID),
UNIQUE KEY identifiers (identifier_hash, client_identifier, user_id),
KEY identifier (identifier(7)),
KEY created_at (created_at),
KEY user_id (user_id),
KEY ip (ip)
);`
