Acer Aspire L320 stopped working, HELP!

hello, ive had an Acer Aspire L320 for quite a while now,

ive had it upgraded by a computer shop to make faster with some more ram and brought up the hard drive space to 320Gb and it was running fine till yesterday.

it has been running 24/7 for a while with maybe a restart every 2 months or so, and had no problems with it and now i plugged it in (after a LAN party needing space) and it wont even turn on. it turns on the fans when i plug it in and when it press the power button it doesn't respond and continues to run the fan.

I have alot of experience building computers, but this is my absolute worst nightmare because its so cramped inside. can someone direct me to what i should to to fix it or what to check and/ or replace

 

New power supply would be the first thing I'd try.

 

Sometimes the following will get you going temporarily. Unplug the computer, hold the power button down for 30 seconds. Plug the computer back in and press the start button.