lost com3 port in win7 professional 64bit

Everything was going fine with my Arduino Uno for several weeks, until I
tried to set up Circuit #4 (Multiple LEDs) in the "Viros Ultimate Start
Kit Guide". I wired the board as indicated, loaded the appropriate
sketch, and then attempted to download it to the Arduino. At that
point, I suddenly got an "Problem uploading to board" error message.
When I look in the IDE at TOOLS -> PORT, COM1 is showing (it used to be
COM3). Plus I now get repeated error messages from the system about how
a USB device is not recognized. I am running Win7 professional 64 bit.
There is a wilderness of complaints on this Forum about lost COM ports
in win7 systems, each complaint with a multiplicity of "solutions", but
it is not clear which (if any) actually work. I have tried a few with no
success. Help would be appreciated.

Thanks in advance

Instead of us listing all those possible solutions, why don't you tell us what you've tried? When the board is plugged in, what COM port does the device manager state? Also post any error messages that you receive.

Thanks for your reply. Device manager does not explicitly say anything about Arduino. Under "Ports" it lists "Communications Ports (COM1) and "ECP Printer Port (LPT1). Under Universal Serial Bus Controllers, it specifically lists one entry as "Unknown Device". When I try to download a sketch to the board, I get the following error messages (I chose verbose output upload):
Arduino: 1.6.8 Hourly Build 2015/12/30 06:43 (Windows 7), Board: "Arduino/Genuino Uno"

Sketch uses 1,564 bytes (4%) of program storage space. Maximum is 32,256 bytes.
Global variables use 29 bytes (1%) of dynamic memory, leaving 2,019 bytes for local variables. Maximum is 2,048 bytes.
C:\arduino-nightly\hardware\tools\avr/bin/avrdude -CC:\arduino-nightly\hardware\tools\avr/etc/avrdude.conf -v -patmega328p -carduino -PCOM1 -b115200 -D -Uflash:w:C:\Users\Neal\AppData\Local\Temp\build8c291606b4f80d24d5a673d5620df26e.tmp/sketch_feb19d.ino.hex:i

avrdude: Version 6.0.1, compiled on Apr 15 2015 at 19:59:58
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2009 Joerg Wunsch

System wide configuration file is "C:\arduino-nightly\hardware\tools\avr/etc/avrdude.conf"

Using Port : COM1
Using Programmer : arduino
Overriding Baud Rate : 115200
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xae
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xae
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xae
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xae
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xae
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xae
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xae
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xae
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xae
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xae

avrdude done. Thank you.

Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.

This report would have more information with
"Show verbose output during compilation"
enabled in File > Preferences.

Looks like a driver issue, although I know that the board is not on COM1. Follow this to try and reinstall driver, https://www.arduino.cc/en/Guide/Windows#toc4

Is this Uno a clone?

I run into problems at step 3 of your instructions, because the device manager does not explicitly mention Arduino. Attached is a print-screen of my device manager. What should I pick?
In response to your question about whether the Arduino is a clone, I don’t think so. I had taken some pictures of it to show you, but discovered that, now, all my USB ports have apparently been messed up, and I can no longer upload from my camera to the PC.

Looks like your OS is screwed up. Hopefully you have the OS CD to repair.

Originally installed from a (legal) OEM disk. Do not believe I ever made a repair disk
(my bad). Perhaps it is time to upgrade to Win10. I have this set up as a dual boot with Ubuntu.
Should I anticipate any problems?

Before you do a lobotamy (?) on your computer, was it working with the older IDE?

I had installed the newest 1.6.7 and nothing seemed to be right. Reinstalled the older 1.6.5 and things are fine.

nlenoden:
Originally installed from a (legal) OEM disk. Do not believe I ever made a repair disk
(my bad). Perhaps it is time to upgrade to Win10. I have this set up as a dual boot with Ubuntu.
Should I anticipate any problems?

I think upgrading to Win10 is a bit drastic.

You could develop in Ubuntu.

I did. Now I am over on Linux Mint 17.3 and I run 1.6.7 IDE.

Amazingly, I have actually been able to SOLVE this problem, and the answer is AMAZINGLY SIMPLE.
I can't I discovered it on my own, I just read about it elsewhere on the internet.
Are you ready? Here it is:

  1. Shut down the computer
  2. Unplug it
  3. Wait a minute
  4. Plug it back in.
  5. Problem solved.
    According to the guy who discovered this, even when you shut the PC down, there is still power being delivered to the mother board. If something goes wrong with the board, unplugging and waiting will allow the motherboard to reset itself, thus fixing the problem.
    I can't say this will solve all the "lost COM port" problems I read about on this forum, but it worked for me.

Incidentally, I did try to switch over to Ubuntu (I have a dual boot setup), but not being much of an Ubuntu guy, I found it quite confusing. Maybe it will be simpler, now that the mother board has reset.
I'll try again & let you know.

Many thanks for your attention.