IWhen I turn on my computer the monitor comes up black with no input and the keyboard and mouse will not work, it is not the monitor? please help I can't get to anything to try and fix it, it is a sony desktop

How can you be sure it's not the monitor? Did you try a different Monitor on your Sony? Try the Sony?? Monitor on another Computer? Is "No Input" a message you see on the Monitor. Have you changed anything on your Desktop lately? New HDD, RAM upgrade? Had it apart for any reason? Has anyone else used or worked on it. Do you hear any BEEPS on startup. 1-2 short/long? Other, including NONE. Please post some info on your Computer. Model # Central Processor type and speed. installed Ram. Any previous, recent other Problems? Lightening storms, Power outages. I'm just full of questions? Hope you've got some answers. Start by checking all external connections, try a different wall outlet. If you've upgraded RAM, reseat the RAM or put the old RAM back in, 1 Module at a time, then check all connections inside the case. Of Course have the power off for this and switch the POWER SUPPLY off at the rear of the Case, or unplug from the wall. Let us know what you find. There is nothing to learn from someone who already agrees with you.

no one has use my computer, no lightning, but I did install some new ram 2 512 and took them out and still the same and try one at a time still the same, I did try my monitor on another computer it was fine and the no input comes up when I trun on my computer, but before this it didn't seem to run good as far as the screen was looking, it is a sony viao rz46g desktop media center it has some age on it but it has always done great, any hope will be apreciated, I am at witts end with this, thought about graphic card but then that wouldn't cause my mouse and keyboard not to work, what about a virus? wonder if I did something to it when I install the ram? HELP, can't afford a new computer