Malfunctioning of Wordpress Admin Cannot Access wp-admin

Please I need help. I worked on a blog for a client and he did some work on it that resulted in the malfunctioning of the blog. Now I cannot access the dashboard of the blog what can I do?

Maybe he changes the URL of the blog go to PHPMyAdmin and open the table settings and see exact your URL's what you are using .. like I am on localhost/WordPress a row in setting table which will show the exact URL if the URL not matching please change it.