how to safely remove arduino form windows... after uploading code....???

Using Arduino IDE 1.x
1

i brought two arduino nano..

i uploaded the code to the first one.. and unlpugged the cable..
then i again connected and uploaded the same code with some changes and unplugged the cable..

i done it 5 - 7 times

when i connect the nano to computer to upload the code ,,, error message appeared that... programmer is not responding..

so i took the second one...

done the same steps...

it worked perfectly till the 9 th uploading... the same error message appeared again....

please help me

2

Settings might accidentally been changed.

Correct port selected?
Correct board selected?
Correct processor selected?

If yes, enable verbose output during upload in file->preferences, try to upload and post the results here (use the copy error messages button in the IDE).

Which IDE?
Which version of board manager?
Is your board an original or a clone?