Arduino was working fine at first and now its not recognized

I setup my Arduino Uno with an LCD display and 12v power adapter to power it without the USB cable. Everything worked fine initially, but now when I've went to tinker with it again my board isn't recognized. I was using the COM4 port and now that option isn't available. Here's the error code I get when trying to upload code to the board:

Arduino: 1.8.4 (Windows 7), Board: "Arduino/Genuino Uno"

Sketch uses 2986 bytes (9%) of program storage space. Maximum is 32256 bytes.
Global variables use 65 bytes (3%) of dynamic memory, leaving 1983 bytes for local variables. Maximum is 2048 bytes.
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0xbd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0xbd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 3 of 10: not in sync: resp=0xbd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 4 of 10: not in sync: resp=0xbd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 5 of 10: not in sync: resp=0xbd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 6 of 10: not in sync: resp=0xbd
avrdude: stk500_recv(): programmer is not responding
Problem uploading to board.  See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.
avrdude: stk500_getsync() attempt 7 of 10: not in sync: resp=0xbd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 8 of 10: not in sync: resp=0xbd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 9 of 10: not in sync: resp=0xbd
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0xbd

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

Anyone have any idea why this is happening?

What does the Device Manager show?