OS Not opened
When i tring to start my mac, the operating system cannot be opened, even if i restarting or shuting it down and start it again.
Just the background only appeared.
How can i repair or fix the OS
The 2nd question, i have to take a backup in time machine by a storage capacity equal or more than the data size in my mac, or can i use a storage less than the current data by selecting specified data plus the os to take a backup
Mac Pro, OS X Mountain Lion (10.8.2), Os not opened