If you experience problems not described in this knowledgebase, or current solutions do not work, there are 2 other things you MUST check before contacting support team.
1. Please log on to cPanel of website you experience problems with, and click "Error Log" icon. It will display a list of problems detected on your website, so you may find what causes errors and fix them yourself. For example, if you can not open some files on your website, and error log displays something about wrong permissions, you need to set correct permissions for these files. Error log feature may help you to solve 99% of problems yourself.
2. If you can not upload files to your account, use webmail, receive emails, setup new cronjobs, change password for cpanel/email or do other tasks, it's possible your account is running out of space. You should login to your cPanel and check how much free space you have. If your account uses all space assigned, you must delete some files or upgrade your account. As soon as your account will have more free space, all these functions will start working