This is on basis of chat with you it looks that your admin_rule table get clear it is not able to find a rule for your role.
For this you have to create entry in this table for your role which is in admin_role table. or else you can upload a backup of your old table if you have.
To make a user login 3 tables are taken into consideration whose relation are as follows.
This table stores all data of user information like name, password,create date, active or not etc.
This tables holds data of roles for users created in magento. for admin it is Administrators.This tables links to admin_user by user_id column.
This table is used to hold a data related to permission for a role. This table link to admin_role table by role_id column.
In your case you can use https://drive.google.com/folderview?id=0BweKwHQ_asV2TnJreDZnRWszME0&usp=drive_web this link which will create above table with admin as user name and admin@123 as password
before importing this table take a backup of your existing tables.
after making login rest password for your user and you are done.
Use below mentioned MySql for generate new admin user :
LOCK TABLES `admin_role` WRITE , `admin_user` WRITE; SET @SALT = "rp"; SET @USERID = "user_id"; /*Replace user_id with your user_id*/ SET @PASS = CONCAT(MD5(CONCAT( @SALT , "Password123") ), CONCAT(":", @SALT )); /*Replace Password123 with your password*/ SELECT @EXTRA := MAX(extra) FROM `admin_user` WHERE extra IS NOT NULL; INSERT INTO `admin_user` (firstname,lastname,email,username,password,created,lognum,reload_acl_flag,is_active,extra,rp_token_created_at) VALUES ('Firstname','Lastname','firstname.lastname@example.org',@USERID,@PASS,NOW(),0,0,1,@EXTRA,NOW()); /*Replace Firstname,Lastname,Email with your details*/ INSERT INTO `admin_role` (parent_id,tree_level,sort_order,role_type,user_id,role_name) VALUES (1,2,0,'U',(SELECT user_id FROM `admin_user` WHERE username = @USERID),'Firstname'); /*Replace firstname with provided firstname on above insert*/ UNLOCK TABLES;
Note : If you are using table prefix then please add your table prefix in each table before using this query.