trouble on code uploading

hi guys
i was loading my code to the arduino uno r3 but on uploading it gave an error and no board is working.

avrdude: stk500_getsync(): not in sync: resp=0x30

kindly help so that i can continue

What to the L, TX, and RX lights do when you try to do an upload?

guys found the problem
it was the problem with the COM selection.
thanks