@vasili333 Be aware that there is a limit on the number of posts a new user can make. So avoid making short posts and try to combine your answers in a thorough long post.
Anyway, I understand that you were flashing OpenWrt, and presumably you didn't notice any error, though it's not booting now.
Things to try:
- Connect via cable. See if you can access the router.
- Set your PC Ethernet card to static IP in OpenWrt default IP subnet (e.g. 192.168.1.10) and try to ping the router (192.168.1.1).
- If in doubt that flashing might have not completed, try setting the IP of your PC to stock firmware IP subnet and ping stock IP.
If none of the previous works, then it would appear that the router was bricked.
The router page on the Wiki https://openwrt.org/toh/netgear/netgear_r6220 mentions debricking using nmrpflash. If you say you tried it but it didn't work, could you elaborate abit about what exactly you did, and also you computer operating system (Windows, I presume?).
The idea would be to revert to stock using nmrpflash as per the page, then flash OpenWrt again. I don't know if you could flash OpenWrt directly from nmrpflash.
Also, to unerstand why flashing for the first time went wronig, you may liek to read through this
Support for Netgear R6220 by @rsterz (and you could also send him a message to see if he can help, since he unbricked his router before).