Can't login to Magento admin

Question

I have magento installed in a subdirectory. www.domain.com/subdir/magento

This site worked perfectly at one point. I changed nothing, until my client said he could

Answer 1

Check the cookie configs in core_config_data table and check if your session is being saved on db. In my case, someone just changed the cookie domain and the cookie path with a wrong value.

You can also check this on the node in your app/etc/local.xml. If it's on db, maybe you should change do files to be able to clean the session data directly on var/session dir.