Cannot upload Code to Arduino Uno.

Hey guys, I've got following problem:

Whenever I try to upload my code to the Arduino board it gives me the error

avrdude: stk500_getsync(): not in sync: resp=0x00

I have already bought a new Atmega328P-PU and tried to burn the bootloader, this gives me the error

avrdude: usbdev_open(): did not find any USB device "usb"

When I connect the USB to the board the LED's are on + when I push the reset button the orange LED is flashing. Is there a probable cause for this? It might be possible that I fried my board when experimenting with a transistor, but I cannot explain to myself why that should be the case. I can show you my breadboard of the last experiment if wanted.

I hope you're able to help me with this, I have invested (i.e. wasted) about 5 hours on this error already and have no clue how to solve it. If you need additional information, just tell me.

Thanks in advance,
André

Which arduino IDE and which computer OS?

...and what did you use to burn the bootloader. It looks like no programmer was connected to the computer.

mart256:
Which arduino IDE and which computer OS?

I'm using Arduino as IDE, and Windows 7 as OS.

Budvar10:
...and what did you use to burn the bootloader. It looks like no programmer was connected to the computer.

Got an AVR-ISP from a friend. Might be broken though, but I thought it was worth a shot.
If there's no other sollution I will buy one myself.

Div3x:
I'm using Arduino as IDE, and Windows 7 as OS.

Got an AVR-ISP from a friend. Might be broken though, but I thought it was worth a shot.
If there's no other sollution I will buy one myself.

I mean, which version, 1.0.6 or 1.5.8 or another?

mart256:
I mean, which version, 1.0.6 or 1.5.8 or another?

I tried both of the above, none worked.

This error avrdude: stk500_getsync(): not in sync: resp=0x00 simply means that averdude does not obtain an answer but it has a several reasons. One of the reasons is missing bootloader.

When I connect the USB to the board the LED's are on + when I push the reset button the orange LED is flashing. Is there a probable cause for this?

If bootloader is present and is working corectly L led should flash 3 times after reset or power on.

Budvar10:
This error avrdude: stk500_getsync(): not in sync: resp=0x00 simply means that averdude does not obtain an answer but it has a several reasons. One of the reasons is missing bootloader. If bootloader is present and is working corectly L led should flash 3 times after reset or power on.

The L LED is flashing 3 times upon reset or power on, meaning the bootloader should be present.

Try another cable, port, computer to exclude those things. You can also switch on detailed info for upload and provide an output, but I am not expecting any surprise. Can you get another Arduino from friend or working programmer?

I just solved this 10 minutes ago. Seems like it was a compatibility problem with Windows 7 or something like that. I just installed Linux Mint on my notebook and tried it there, it worked. Seems like I have to work on my notebook for programming but I am happy it works. I don't think it's worth trying to fix it on my Windows PC, since it's way more handy on a notebook.
Thanks for all of your help!

why i can't upload code to board?
the error message:

avrdude: ser_open(): can't open device "\.\COM3": The semaphore timeout period has expired.

i am using Arduino IDE and my OS is windows 10