PC turns on and fans blow screen will not come on

Im guessing you meant black screen totally never text there.
does the monitor work on other PC as it must?? simple no?
if yes, it is good and the unstated PC is bad.
if not, the monitor is bad, if this old monitor is very old
2 things fail.
1: CCFL lamps inside all died long ago. 2010 or older.
2: the screen saver inside IT is turned on, turn that off.
push the menu button on the LCD monitor.
then in the OSD turn off sleep TIMER clock..

lets say unstated PC is dead.
1: is the fans dead,? if desktop 2 fans must be good, spin and blow air and not be packed up in lint as most old PC are.
heard ,seen to turn, and felt to blow.(air flow must happen)
2: does the DVD tray eject.

If it's a laptop, you can plug in a monitor to see if you can get a signal there. That might tell whether the problem is the graphics card or the screen. There's a Fn/Fkey combination that turns signal on to both monitors; you may need to press that combination to use the monitor.

the laptop if older than 2009 , (NO PC stated.)
will have bad CCFL back lamps.
remove the big battery now,
run on AC pack only
still dead screen?
the fan must blow, seen/heard or better felt.
if fan is dead PC needs service, ask
if fan blows test the screen with a flashlight in dim room.
if you see data now, with the flashlight, the CCFL tubes DIED.

It could be several factors. I would start with opening the case side door and blowing out all the dust and making sure the CPU fan is working. If it overheats the PC will turn off to protect itself.

Turn unit off.

Try taking compressed air and blow out dust from the cooling vents. If you get the right one (where the fan is) you should hear the fan change speed.
Power up and see how it works. I have seen many laptop issues like this go away after blowing out with air.

Check the color of the power light on the monitor (screen). If it is orange, that means you're getting no signal from the CPU to the monitor. If that's the case, check the signal cable going from the CPU to the monitor to make sure it hasn't been disconnected.

Does it work with the adapter? Battery ? Does it post? If it does not post you may have a bad cmos or bad power supply.

Often that will happen if the memory (RAM) is not seated properly. Unplug the machine and open the box. Find your RAM and make sure it is firmly seated. Plug in machine and turn on.
I have seen one situation where the machine couldn't find a keyboard and did the beep sequence.

Good luck.
Semper Fi,
Z

a1240n (desktop)
the fans are dead. right? why not start with sounds.?
Desktops have 2 or 3 fans
1 in the PSU that must run fast,. does it ,heard and seen?
2: the CPU, has fan for sure, and must spin, blow air across the CPU heat sink not packed full of lint all PC this old ,always have,
3:then the GPU video card may have a fan that again must work.
so if all fans are dead, the psU IS BAD,

SURE I ASSUMED IT'S PLUGGED IN, AND THE WALL HAS POWER, after all

answering for
dead PC
dead black screens, never any text.
no sounds from PC
no monitor stated(i'd need that if the PC made sounds)

Something not connected properly, or possibly hardware issue or failure.