what is this error?

Binary sketch size: 2,144 bytes (of a 258,048 byte maximum)
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer
com port is showing but still cant upload my program…

you might have chosen the wrong board type?

it was working fine for past several months but from tommorow it started…

Did you plug it into a different USB port? You might have to change serial ports.