i changed my laptop's charger my laptop works but external display does not work what to do

[Surya_]

it runs windows8 os I had problem in charger so i changed the powerbutton is on in laptop but no respond in monitor

 

[Laptop_Nerd]

Hi,

Do a hard reset first, remove the battery and AC adapter then press and hold the power button for 20 seconds. Plug just the AC adapter and see if it boots up if it does you can connect the battery as well. If it doesn't boot up still try and reseat the RAM, take them out then make sure they are all seated properly into each memory slots. Worst case is either your motherboard or display is faulty already and needs replacement. As you mentioned the external monitor doesn't work either so it's leaning towards to be a motherboard problem.