If you need to manually disable a module you can do so in the database. Before you start, do a mysqldump (or export) of your Drupal db to a local file in case things go wrong and you need to roll back.
In order to perform these commands one must have access and proper permissions to execute MySQL commands. These commands can be executed with GUI like phpMyAdmin, or just the MySQL command line interface.
To disable a module via phpMyAdmin you must login to phpMyAdmin. Then you must locate the database where Drupal is installed. Once you have done so look for the "system" table. Click and open it. Click to browse the table. Find the record for the module that is causing the problems and select the edit function. Set the status to "0" and save.
MySQL command line
To disable a module using the MySQL command line, run the following SELECT to look at the state of your data before the change. This will help you to find the full name of the module too.
See all the modules enabled:
SELECT name,status FROM system WHERE type='module';
See if a particular module is enabled:
SELECT name,status FROM system WHERE name='module_name';
Disable your module, set the status to 0 for the module name that you want to disable.
UPDATE system SET status='0' WHERE name='module_name';
Enable your module:
UPDATE system SET status='1' WHERE name='module_name';
Check your handiwork using the SELECT statement again.
Drupal 7: Clear Cached System List
On Drupal 7, you must still follow the procedure above to disable the module in the system table. However, data from the system table is cached. This means that even though you updated the system table, Drupal may still think the module is enabled because its cached copy of the system table is not up-to-date.
The cached copy of the system list is in the cache_bootstrap table. Clear the cached copy of the system list as follows.
If you are using phpMyAdmin, find the "cache_bootstrap" table, and delete the record with cid="system_list".
MySQL Command Line
To update the cache using the mysql command line, type:
DELETE FROM cache_bootstrap WHERE cid='system_list'