Before doing the following, long shot but something for you to try, shut down and restart the computer a couple of times using the power on button, this to see if you can force the computer to start in the Windows recovery environment (RE) I suspect that it may not but want to suggest as much as I can before you open up the computer.
If no Windows RE you will need to open up the case, check for any loose connections and try reseating the RAM and any add on video card if one is present.
The following checks require the computer case to be opened so take the following safety precautions first, disconnect the power cord from the wall socket, press the computer power on button for around 20 seconds to get rid of any residual charge in the system, remove the side of the case, take anti static precautions before touching anything inside, you can do this by touching a bare metal part of the case or the PSU.
Have a pencil and notepad to hand.
Remove each stick of RAM and blow out the memory slots.
Insert the first stick of RAM in memory slot one, reconnect the power and in the case of a desktop computer the video to screen cable.
Power up the computer and see how it goes.
Make a note of the results.
Repeat the procedure until the first stick of RAM has been tested in each memory slot and the results written down.
Remove the first stick of RAM and put it to one side on top of a piece of paper with the number one on it for identification purposes.
Repeat the procedure with all RAM until each stick has been tested in all slots, the results written down and the sticks identified numerically.
Please note that some MBs (motherboards) will not boot unless there is RAM in slot one, please advise if this is the case here.