It is a common problem. Many of the administrators would have undergone this situation as we would have lost mobile or uninstalled authentication app and also have lost backup code somewhere else. Simply follow this step to log in.
Step 1: Go to Your hosting service
Step 2: Go to File Manager
Step 3: Open the folder Library
Step 4: Open the File Config.php
Step 5: Type the following code in last line of Config.php
$config['enableTfa'] = false;