It sounds like your hard drive was either dying or getting severely corrupted. It has now reached the point where it no long is usable.
Without an install DVD there is not much you are going to be able to correct the situation. A new Snow Leopard install DVD can still be purchased from Apple.
Do you at least have a backup of the data on your disk?
Hi , and a warm welcome to the forums!
Allen is likely right, but...
Tough without the Install disc, but some things to try...
Does it boot to Single User Mode, CMD+s keys at bootup, if so try...
Repeat until it shows no errors fixed.
(Space between fsck AND -fy important).
Resolve startup issues and perform disk maintenance with Disk Utility and fsck...
sorry to intrude..... BDAqua can you help?
these are my options in system preferences>displays>
resolution, brightness, and mirroring
I am using DVI connector, everything worked fine until 10.8.4 latest upgrade...
Your problem is completely different to that of the original poster of this thread, and it can be very confusing for everybody if we try to answer more than one question in each thread.
In order for us to give your problem our undivided attention to try to solve it, would you kindly start your own thread, describing the trouble you are having in the fullest detail, including completing your details to show what Mac you are using, what operating system, and what version of the application in question. Please remember to post in the forum relevant to your hardware or version of OS X, namely Mountain Lion.