This blog post explains a nice way of disabling your WordPress plug-ins in case something has gone wrong with your blog and you are unable to log into your admin area in order to rectify the problem. In most of the cases it is the plug-ins that cause problems in a typical WordPress blog unless something has happened at the server end. In such cases, if you can login to your admin area you can first deactivate all your plug-ins and then activate them one by one to see exactly at what point the problem begins to manifest.
Or sometimes you cannot log into your WordPress admin area. So if you cannot login how can you disable the plug-ins and unless you can disable the plug-ins, how can you rectify the problem?
The best way to do is, according to the above-linked blog post, login to your FTP account (using one of your favorite FTP clients installed on your desktop, or using your web host’s Control Panel file manager), go to your /wp-content/ folder and rename your “plugins” folder to something like “pluginsss”. The basic idea is, when WordPress looks for this folder, it shouldn’t be able to find it.
Then go back to your browser window and go to the page that you use to log into the admin section of your WordPress blog. This time you should be able to login (if one of the plug-ins were causing the problem, that is) with a slew of errors saying that the plug-in files were not found. Since WordPress cannot find plug-in files, it disables all the plug-ins.
Then you can go back to your FTP account and rename “pluginsss” to “plugins”.
Then go back to your WordPress admin area and when you go to the plug-ins section, you will see that all the plug-ins are there but right now they are disabled or deactivated. You can enable the plug-ins one by one and see exactly which plug-in is causing the problem.