Hello 
! So everything with my board was fine. Then I switched other power supply and then L and On led's starded to blink. So I switched to my original power supply and now there are turned on L, Tx, Rx and On led's.
Also I can't upload anything to my arduino un r3 board. Any suggestions on what should I do?
You posted this in the Arduino Zero section. You mention Also I can't upload anything to my arduino un r3 board.
So what do you have?
Sounds like you seriously blew something up. Throw the board away, buy a new one and don't make the same mistake again.
Which mistake, you may ask? We have no idea, there is not enough detail in your post.
Sorry for posting this topic in Arduino Zero. I am new to this forum, also in arduino. Isn't there any advice for this problem? Maybe somehow I can completely restart arduino? Sorry again.