Well I just registered on this forum to thank you all for such great advice! I have a lumia 1020 and it wasn't starting up..
So here's what happened, as any usual day, I left my phone on charge whilst I was using my laptop, before going to sleep I took my phone off of charge, powered it off and put it underneath my pillow. The next morning I wake up, try turning on my phone and it vibrates. I left it in my pocket till it turned on then when I took it out again, it wasn't turning on at all. And yes, just like you guys, I was damn scared.. :3 but yeah, I tried what you all did and I found the solution to my problem and it started. So thank you so so much! I'm really happy.