What can I do if a player just stops playing and leaves me hanging for 20 minutes ?

I was down on this game and suddenly took the queen, now i am left for 20 - 25 minutes on a 30 min game waiting because he probably just got up and left the computer. Happened to me several times that's why i'm asking.

Thanks.

Also yay I took the queen but i wish i could have developed further

My first piece of advice would be this...

Learn how to play chess.  Learn and understand that the clock is part of the game.  Learn, understand, and accept that your opponent is free to use his time as they see fit.  

He didn't play any more and lost on time, 25 minutes past and didn't move anything else.

Also i play chess since i am 7 y o i am 27