I disabled the arduino while loading the sketch. Now it gives an error when loading the sketch

It's my first thread on the forum, so... Here is the situation: I was uploading the sketch to the board (Arduino Nano V3.0) and accidentally disabled it before full load. Now I have such errors in the Arduino IDE's output window when I load sketches: “avrdude: stk500_cmd(): programmer not in sync” and " avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51". What is this and how can I repair this?

What means, "disabled it"?????

Why did you delete your post?

Disconnected from pc.

Does the serial port appear in the tools menu? Is it selected?
YARN | Have you tried turning it off and on again? | The IT ...

Serial port appears when I connect the board. The board writes strange characters "�" (Checked it in Serial Monitor).

When does it do that?

When connected.

in a loop

Post the program you were trying to load, using code tags. Perhaps it was correctly uploaded, but there are other errors (like the serial Baud rate).

Please read and follow the instructions in the "How to get the best out of this forum" post.

Why would you even care about that? It's probably serial output from your sketch.

I thought you had an upload problem....

Does the compiler now not complain, finishes the upload with completion message?

It's not finishes the upload. I have only error messages
avrdude: stk500_cmd(): programmer is out of sync avrdude: stk500_cmd(): programmer is out of sync avrdude: stk500_cmd(): programmer is out of sync avrdude: stk500_cmd(): programmer is out of sync avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x00

Are you sure you selected "nano"?

Yes

Did you
YARN | Have you tried turning it off and on again? | The IT ...

Yes, more than once

Computer?

Tried it, too

Do you have a second PC or a second Nano to try?

I have the second computer, but no access to it now. And only one Arduino