It burns, it burns! 
There could be a number of reasons for it. As a rule of thumb, the WordPress Login Screen is always at
http://yourdomain.com/wp-admin
or if you’ve installed WordPress in a subfolder it’ll be
http://yourdomain.com/subfolder/wp-admin
If you get a White Screen of Death instead of the login screen then you have a plugin or theme failure – which means a lot of work…but I can always help you rectify this should you ever find yourself staring at a blank screen.
Raise a Support Ticket and we’ll work something out if you need help.