Log in to phpMyAdmin. Select the corresponding database on the left.
Click on wp_users on the left pane which should list all users for the WordPress site. Look for admin on the user_login column and click the Edit button which has an icon of a pencil.
At the user_pass row, change the value to 5f4dcc3b5aa765d61d8327deb882cf99 and click the Go button.
Now go to your wp-admin page and log in with the following details:
Username: admin
Password: password
Don't forget to change your password from the profile page!