Im very new to Arduino and recently bought a redboard (https://www.sparkfun.com/products/12757). I used the board once yesterday it worked fine and I was able to do basic stuff like blinking LED using ports 8 and 9. However when I plugged it in today the board is repeating the blinking LED whenever I plug the LED in that I uploaded to it yesterday. The board is not detected by Windows any more, and does not show in the devices manager now, there is also no sound when I plug it in. When I try uploading a new sketch I get the following problem avrdude: stk500_getsync(): not in sync: resp=0x00. Any help would be greatly appreciated, thanks!
Sounds like the USB port, USB cable, USB connector, or FTDI chip is not working. Try a different USB port on your PC.. Try a different USB cable with various USB ports on your PC. Examine the USB connector on the board to make sure the pins are not bent and the solder joints are solid. Examine the FTDI chip (next to the USB connector) to se that all the pins are still soldered correctly (no shorts or broken joints).
If all that fails your FTDI chip is likely defective or damaged in use and needs to be replaced.
I figured it was an electrical problem because even if you didn't have the FTDI drivers installed the chip should have been recognized as a USB device. Since you said "does not show in the devices manager now" it wasn't even getting that far.