How to backup my data when my phone is crashed

Registration date
Saturday August 8, 2015
Last seen
August 9, 2015

I cannot copy my files on phone to PC or take backup, as some water entered inside my mobile phone and the display is off. The repair costs nearly the cost of phone.
So i thought of buying a new phone instead.
But, I have very important files on my phone and i want to recover them.
My phone connectivity setting at the that time is "Charge only" (not Mass storage). So it is not connecting to my PC.
Please tell me how to recover them as soon as possible..Please help me out in solving this issue. please....

Thanks in advance