My laptop once again is displaying a black screen

My Toshiba L355D will not always turn on the screen when I turn on the computer. Sometimes I have to turn off and turn on the computer for about 10 minutes of on and off before it finally turn on. I did the suggestions as hit the FN key plus the F4 and F5, nada..nothing, big dud. I do not use a battery in this laptop, the battery went bad about a year ago, so I never replaced it. I just use the power cord. I took the memory out switched them, even tried to start the computer without the chips in place..nothing , zip, nada..I do notice now the my right side USB port does not seem to work when I plug thing into...eg...wireless mouse thingie, the fan for my laptop to keep cool , I jiggle the cord at the USB and the fan runs and shuts off by itself. So I use the 2 USB ports that are available on the left side without incident. I was thinking either the on/off switch is good or bad I'm not sure. Or is it caused by the faulty USB PORT?

ANY HELP would be really appricated..thank you

Hi Raichel I did as you suggested and my computer worked great for a few days.. Now it's back doing the same old thing it did before. I rechecked the settings you advised me to do and they were fine, no changes in them.

Any other ideas do you have? Please help.

Raichel, I did all these steps as you said to do. Everything was fine for a few days, now my computer is returned to the monster it once was. Sometimes it starts right up, other times it takes as much as 5 to 10 minutes turning it on/off to get the screen to come on. Any other ideas what might be wrong?