LG w2452tx monitor won't turn on and the power light is just flashing. How can I get it to turn on?

Check the electrolytic capacitors inside in the power supply board portion. replace all busted ones.

you need a mainboard or powersupply

check the vga cable which get loose connection then the signal from pc not recognized.

switch is usually at side just fill it just takes few seconds to turn on / maybe the lcd is not working an more gotta change it

To find out where the problem is, you will have to try this monitor with another PC or try another monitor with this PC first to narrow down the problem.
Please post back after what you find out so we can help you further.

Basic LCD monitor and TV troubleshooting guide:
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r7406380-tv_training_manuals
Failed TV and Monitors pictures: http://s807.photobucket.com/albums/yy352/budm/

Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague

Capacitors kit: http://lcdalternatives.auctivacommerce.com/ he can make you a set of caps for you.
Or www.digikey.com just make sure to use caps with low ESR, 105c, high ripple current, long life rating such as PANASONIC FM or FC series.

I had the following symptom: No power on, or only sporadic power on, power-on light blinking, etc.
Problem was: Capacitor C202 & C203 (both 1000 uF, 16V) on the PS board had lost capacity, tested only approx 45 uF. Replaced, everything works fine now! Cost: 20 cent.

First--was it working?
Did it suddenly stop?
When you see the LG logo, then it goes away, does the power light turn from green to amber? Sounds like that doesn't happen.
So--if you are getting a signal, you should see something.
If there is no signal, then the power light should change from green to orange.
With no lights at all, I suspect a faulty monitor.

it seems that there is a problem in the lcd back light or may be in power supply section

are you getting a check signal cable message? any on screen instructions?

try the cable, if it works on another monitor, then sorry to say but your monitor is fried