user48730: I have 2 types of Pro-Micro(as shown here), both 5v, micro-usb, which worked as expected, until, accidentally were flashed as 3.3v using the Arduino IDE.
At first I thought that the fact it stoped working right after, has nothing to do with that error, but since again, did the same mistake, I understand that this is no coincidence.
After doing so, boards seemed to be powered on ( leds are ON ), but are not found under port in the Arduino IDE.
Are they really can be destroyed by such an error ?

user82220: I had the same issue with a promicro wired in to a button box, before i found out that you need to upload a sketch....I know...I`m a noob, I was trying to rename my button boxes board to a Sparkfun board but I think i had 3.3v 8mhz selected instead of 5v 16mhz, as a result my board was not detected under comm ports and gave a driver error, given that...with my board at least there is only an 8 second delay in which you have to select the correct comm device and then upload a sketch, I shortened the process by opening IDE and selecting the board type and left IDE with a black sketch, of coarse this does not allow the board to be detected as a usb device but it fixes the comm port issue, instead of using a fiddly wire jumper i just used a small screw driver to jump the gnd and reset contacts and quickly selected the boards comm port in IDE then upload  with out a delay, by the time IDE actually recognizes a device you actually have closer to 3-4 seconds to react....but its doable.

user48730: Holding RST and GND pins after re-connecting USB, showed it on port menu.
needed another such holding, prior to upload.
All good now.

48730: <p>I have 2 types of Pro-Micro(<a href="https://www.aliexpress.com/item/32849563958.html?spm=a2g0s.9042311.0.0.56654c4d46zEGT" rel="nofollow noreferrer">as shown here</a>), both 5v, micro-usb, which worked as expected, until, accidentally were flashed as 3.3v using the Arduino IDE.</p>
<p>At first I thought that the fact it stoped working right after, has nothing to do with that error, but since again, did the same mistake, I understand that this is no coincidence.</p>
<p>After doing so, boards seemed to be powered on ( leds are ON ), but are not found under <code>port</code> in the Arduino IDE.</p>
<p>Are they really can be destroyed by such an error ?</p>
 82220: <p>I had the same issue with a promicro wired in to a button box, before i found out that you need to upload a sketch....I know...I`m a noob, I was trying to rename my button boxes board to a Sparkfun board but I think i had 3.3v 8mhz selected instead of 5v 16mhz, as a result my board was not detected under comm ports and gave a driver error, given that...with my board at least there is only an 8 second delay in which you have to select the correct comm device and then upload a sketch, I shortened the process by opening IDE and selecting the board type and left IDE with a black sketch, of coarse this does not allow the board to be detected as a usb device but it fixes the comm port issue, instead of using a fiddly wire jumper i just used a small screw driver to jump the gnd and reset contacts and quickly selected the boards comm port in IDE then upload  with out a delay, by the time IDE actually recognizes a device you actually have closer to 3-4 seconds to react....but its doable.</p>
 48730: <p>Holding <code>RST</code> and <code>GND</code> pins after re-connecting USB, showed it on <code>port</code> menu.
needed another such holding, prior to upload.</p>
<p>All good now.</p>
