wvmarle:
As your USB doesn't react I guess that means the USB to TTL chip is broken.Very likely though that the ESP8266 chip is broken, too. Or at the very least the pin(s) that got to endure 10V, but not much hope for the rest of that chip.
It may be possible to get check whether the ESP8266 is working by connecting 3.3V directly to its Vcc and GND pins. Upon startup the built-in blue LED flashes briefly. Just hold two wires against those pins and see what happens. If no blue flash, not likely it's still working at all.
THANK YOU!!!
3.3V trick worked - resurrected it from the dead, yey 
I tried plugging it to 5V before, but nothing. I didn't had any hope at this point, but tried it anyway, I plugged it to my laptop – nothing as before (no USB sound, no device was seen in device manager), but I took my UNO and pined its 3.3V output to ESP8266 ans It flashes, USB sound appeared and now its seems it works as before, even when I pulled 3.3v away...
Made my day
UPDATE:
D5 pin is dead and ESP8266 chip becomes very hot soon after plugging it in, but code works on other pins. Tried making Pin D5 as INPUT, INTPUT_PULLUP, OUTPUT (low/high), still getting almost unbearably hot to the touch, any ideas?