My hp monitor screen has gone black without any warranty or sign of a problem. the on/off switch is blinking???

a Desktop so old it still has floppy drive, (we trash these the PC)
PS2 keyboard and mouse.wow.

ok, you just found a very old 2003, 14 year old relic PC?
why think any old PC this old can work,, there well be lots of problems!and what monitor is there, name and model number
those same age all fail too, by now with dead CCFL lamps inside.
all do. did, long ago.

so the screen is black and never once shows text , RIGHT?
that is called the black screen of deathh(sic)
HP Pavilion 325c Desktop PC (US) (HP says its RETIRED)
end of the road, support (all)

power on the monitor
see it show, a monitor message log, or words, or even the OSD pops up
then turn on the PC next, see the Screen work show text
or shows nothing , black or the monitor will show.
NO SIGNAL
NO SYNC
OUT OF RANGE.
sleep mode or power saver mode.
The monitor if 2000 an newer will talk to you, it shows failures.
on screen.
does the PSU fan spin, if not the PSU is dead.
and more.
the VGA cables needs to be connected from Monitor to PC.
the power cables both good.
the Monitors menu button must work on front of monitor
or its sign on messages work, it must year 2000 to now.

Sounds as though you have a backlight issue. How old is the monitor?
The keyhole with the lock sign is for a security lock to lock the monitor to a desk so it cannot be stolen.

Actually, the ultra high voltage 'charger' for the florecence (a.k.a. your back light)has gone Kaput...

If your lucky, someone will have a monitor like yours that has the back light come on, but no picture (should get a similar blinking light situation, but a different code. Like... blink, hold, blink blink, hold, blink). In this situation (if your comfortable doing it) you can swipe the exciter from that monitor and put it in your monitor. Obviously this is a more economical way of repairing the monitor.

Just to be on the safe side (as the repair is blindingly easy. 6 screws, pop out, pop back in) DON'T touch any of the back side components. You WILL shock the supreme **** out of yourself. Between the heavy duty capacitors and the ultra high gain transformers on those things you could jump start a bus. So don't be fooled... those little transformers pack a mean sting.

Hope this helps...

Sounds like your video card has gone bad

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/sean_54c3a3dc48a7773c

Hello

My first guess is that the screen circuitry has gone bad - although fixable. Use an external monitor to verify this. If the external monitor is fine then the screen circuitry is bad, if the external screen shows the same problem then the video chip or associated circuitry has gone bad. My company fixes these all the time.

sounds like the backlight has gone....test with an external monitor....if the external monitor works without any problems...the backlight has gone...better to get a professional to do this as its kind of fiddly and involves taking the screen apart

Try it without the rechargable battery connected sometimes the battery shorts and causes problems.
Do you have FN[function] keys at the left side. touch FN key with something else and see if screen comes back.Sometimes you can turn off the screen to send it to the back connected monitor.Connect (extra if you have) an external monitor to the back (vga) connector.If that shows, then you have to ""flutzz" with the FN(function) & F1-F12 keys

A blinking blue light indiactes that your power-inverter board is not putting out what it should. It needs an overhaul which may be a simple as changing out the capacitors on the boards.
It could go beyong that to transistors or even a bad bulb.
It will have to be opened up to do that.
A picture may show visual signs of damage. If you can take one and email it to me , I'll take a look.
Fran

This sounds like the back light is gone on the monitir... to check this look very close at the monitor whet the PC has booted, if you see a VERY dim image on screen then it suggests that the back light is gone.

Many monitors hace a 3 year warranty so I would try a warranty claim before throwing it away

check the warranty online for your screen.. go the the acer support website and look up warranties, and it will ask for a really long number on the back of your screen, and it will tell how long the warranty is good for and what to do with it.
Mine is doing the same thing. flashes white then black and that is all