Why it keeps hanging on the login page?

Until recently, I've still been able to use my MBP for designing and browsing. One day, I opened it and it was stuck on the login page. Can't click the field to enter my password. That's problem #1. When I do a forced restart, it now ends up with a black screen. It doesn't light up with the apple logo etc. This is problem #2. I know it isn't a broken LCD because when I rest my computer for hours or so, it will boot up again and back to problem #1. So it becomes a cycle.

Last I checked, I still have about 40GB free space so I'm not sure where the issue is. I don't wanna pay too much for it to be checked by a service center when I can do the fixing (I'm familiar with computers as I work as a programmer). I've searhed for several answers such as resetting NVRAM etc, but when I press the keys, it won't work.

I'm on Lion OS btw. Any help is appreciated. This laptop has a sentimental value to me.