Why can you not log to your Gmail account?

This can be due to a number of reasons. The first would be you have forgotten your passWord and need to reset it. Another reason would be your email hosting company had closed your account due to a TOS violation.

No matter what the problem the easiest way to either get access back or to find out what is wrong is to hit "Forgot PassWord" or "Reset PassWord". If you setup a backup email or phone number they should send a new passWord your way. If not there should be a helpdesk email account you can contact with that company and one of their staff members can help you.