Hi, new guy here. 
I got a Genuino UNO from school this morning and when I try to upload something (blink) it says:
avrdude: ser_open(): can't set com-state for "\.\COM3"
the board is correctly installed in COM3 and pc settings and drivers are all ok.
It was working some days ago, one of my teachers even uploaded the blink sketch that is still running.
I tought that the problem was the pc, but i've tryed with an old winxp, a win7 pc that uses other arduino boards all the time and my win 10 pc.
I've cecked all the COM settings, reinstalled drivers and IDE several times and it keeps giving me that error.
Searching for the error in this forum i've tried something but it is still not working.
Please I don't nkow what to do anymore, and we would prefere not to threw it away because it's almost new.
Thanks,
Gio